With this guide I will attempt to explain enough of the 3dsmax features/tools so that you can export a model into supcom.
What I won't be touching is modeling and uvw mapping, there are enough tutorials on the net if you want to do that in max.
I'm just trying to explain enough so that total max noobs how to use it just for supcom.
It will really help if you already have experience in any other modeling package, if not I suggest you learn to use your package and general modeling techniques first before modding games.
First you'll have you install my supcom maxtool script. You can get the latest version here:
Supcom maxtool homepage
Refer to the readme in the zip how to install the script.
After installing the script start up max.
Lets take a look at the main max screen:

1) Main toolbar
2) Command panels
3) Viewport controls
Let's take a look at the main toolbar controls you'll be using.

From left to right:
    * Link to parent
    * Unlink
    * Select, currently on, yellow background. With move/rotate/scale you can also select. Sometimes you don't want to manipulate anything so you can use select only.
    * Select from list
    * Move default hotkey: w
    * Rotate default hotkey: e
    * Scale default hotkey: r, has a drop down list so you can select other scaling methods, just press and hold
       -Uniform scale, this is what you'll be using mostly.
       -Non uniform scale
       -Squash
    * Coordinate system
    * Angle snap toggle, snaps rotations to 5 degree steps.
The command pannel:

From left to right:
    * Create
    * Modify
    * Hierarchy
    * Motion
    * Display
    * Utilities
You'll be using the modifier, hierarchy and utilities tabs the most.
The viewport controls:

Top row:
    Zoom, zoom all, zoom extents, zoom extents all
Bottom row:
    Zoom region, pan, arc rotate, maximize viewport toggle
Familiarize yourself with these controls first! Binding these to a key is really usefull. Customize=>Customize user interface.
With these tools I'll show how to setup a model so that you can export to supcom. For the model I'll be using the UEF lobo scrambled around so that it's broken.
Each part of the model has to be a seperate object as the exporter treats each object as a bone. The scm model format does not allow for organic transformations, if you want to make humanoids each limb will have to be a seperate object.
The model:

You will notice a set of axis in each viewport. This is called the "gizmo" you can turn it on/off by pressing x. It will show the axes in the current set coordiante system (see maintoolbar). You can move/rotate/scale on a single axis by selecting move/rotate/scale and hovering over the axis of choice with the cursor and clicking. Each selection option has a different looking gizmo. The gizmo is located at the pivot point of the selected object(s)
For move you will see 3 axes (sp?) and a box joining 2 axes together. Click on the box if you want to contrict move to 2 axes.
For rorate you will see a sphere with circles. Clicking on the sphere and not the circles will arc rotate the selected object instead of constricting it to a single axis.
For scale you will see 3 axes with a triangle object. If you want to scale along all 3 axes (uniform scale) click on the center of the gizmo, this will highlight all the triangle objects. If you want to constrict to 2 axes hover over the edge of the corresponding triangle part. If you want to constrict to a single axis hover over the axis.
Pressing space will lock/unlock the current selection.
Currently the model is a single object. You'll have to detach all the moving parts into seperate objects. To do that you'll have to goto the modifier tab on the command panel.

1) The object name and colour. The object will use this colour if it has no material.
2) Modifier list, dropdown box that contains ALL modifiers in max.
3) Modifier sets. Luckily you can select a set of modifiers and max will show the most important modifiers of that set here. You can edit these sets of create your own. For now you won't need them.
4) The modifier stack. A stack which tracks all the modifiers on the object. The base modifier in the stack is usually Editable mesh/poly/patch. Modifiers with a [+] next to them have extra selection settings. For the editable mesh you can select if you want to manipulate verts/edges/faces/polygons/elements.
5) Configure modifier sets button. Lets you edit/create sets, turn the buttons on/off, select a set. The current selected set has a ">" infront of it.
6) Modifier paramaters. This is where you will find all the paramaters of the current selected modifier. Everything is sorted into different rollouts. Expand every rollout except Soft Selection. As you can see there are a lot of buttons, dials and stuff /o\.
Take some time to familiarize yourself with the rollouts. Note that the edit geometery rollout will change depending on which selection setting you have.
Time to carve up the model into seperate parts.
First some basic viewport commands.
f2) Displays selected faces as solid red faces instead of red wireframe toggle.
f3) Wireframe/solid shading toggle.
f4) Show wireframe in solid shading mode toggle.
Play with them a bit to familiarize yourself with the settings. I suggest you set selected faces as solid red faces on, makes it easier to see which faces are selected.
The current active viewport has a yellow border. To activate a different viewport you can rightclick anywhere in it.
Since supcom models all are seperate elements, not organic objects we can just use the element subselection. Turn element subselection on.
Select all the elements that belong to the turret:

With all the turret elements selected goto the edit geometery rollout and click on [Detach]. This will detach the current selected elements into their own object

Type in the new name "Turret" and click on ok.
Do the same for "Turret_Barrel":

And "Turret_Recoil":

The model has now been seperated into different objects, where each object will be treated as a seperate bone.
Resetting the xform and setting the pivots correctly:
Since the way object transformation matrices and how the exporter uses them isn't the really good (still need to fix this in the script) you'll have to reset the xform of each object. Doing this normalizes the transformation matrix and will ensure that you won't have weird anomalies ingame.
Goto the utilities tab on the command panel. There should be a button "Reset XForm". Select an object and reset its XForm. Do this for every object seperately, don't do them all at once. Doing so might cause problems.
The modifier stack for an object should look like this now:

Notice the base modifier (editable mesh) has a modifier ontop of it (XForm). Now you'll have to collapse the stack. If you have gigantic stacks max will slowdown, collapsing the stack to a single modifier will make it run a lot better then. Since the exporter requires each object to be collapsed to an editable mesh right click on XForm and select "collapse to" or "collapse all". After each object has had its XForm reset and collapsed it's time to set the object pivots, used for bone origins.
Goto the Hierarchy tab on the command panel and select "Affect pivot only" This will show the pivot in the viewports. Since the pivot is used for the bone orientation you'll have to set it up correctly.

Supcom uses a y-up coordinate system, that means the y axis (green has to be pointing up). The z axis (blue) points forwards. x (red) points to the objects left side.
With affect pivot only on, rotate the pivot so that green points up and blue forwards. Turning on angle snap toggle (maintoolbar) lets you rotate in 5 degree steps.

Do this for all the other objects too. Since the pivots are used as bone origins you'll have to move them into place too. Use the move tool to move the pivots. The base object pivot (UEL0103) should be at 0,0,0. To manually set coordinates select the object which pivot you want to move and right click on the move button (main toolbar). This should bring up the following window:

In the Absolute section make sure everything is 0 (note: my unit setup is in meters)
Set all the other pivot points where they should be: (Note, I selected all objects so you can see all the pivots)

Placing reference points:
Reference points are used to spawn effects, shots, attachpoints... anything that needs a fixed point on the model. Each weapon needs a refpoint so it knows where to spawn the shots. Tanks need refpoints so they know where to spawn dust particles and units carried by transports need an attachpoint. Adding reference points is easy. The exporter sees dummy objects as refpoints are exports them accordingly.
To create a refpoint select the Create tab, helpers subtab. Select Dummy. Click and drag to create a dummy object. It doesn't matter how big the size is, all that matters is the pivot.

Again, place all dummies, name them and set their pivots.

Linking the model:
Now you need to create the bone hierarchy. This is really easy to do. Use the link and unlink buttons on the main toolbar to link objects together, or to destroy any links the object currently has. An object can only have one parent, but unlimited children. Linking objects in the view port is done by selecting link, then clicking (this also selectes the object) and holding the button drag towards its intended parent. It should show a dotted line.
You can also link objects in a schematic view. Graph Editors==>Create new schematic view. If you have already created a schematic view you can open it by using Graph Editors==>Saved schematic view==>schematicview instead.

Linking objects in the schemview is done by clicking on the connect button (3rd from the left, next to the mouse pointer) and clicking and dragging toward its intended parent.

The model is now ready to export to supcom!
Goto the utilities tab, click on MAXScript, click on run script. Find the scmtool.mzp you installed earlier and run it. On the utilities dropdown box in the MAXScript rollout select SupCom Maxtool. Default entry in the dropdown box is "convert to mr area lights".
Select the base parent object (UEL0103) and click on "Export .SCM". Select where you want to export to and click ok. The script will now export the base parent and all its children too. (and children of children etc). Dummy objects are converted into refpoints. If anything goes wrong you can check the debug options. This will dump the collected data into a text file where your target scm is.
Alternatively you can make a post on the GPGnet forums or pm me "Robotronic". I prefer a post, that way others can help too. If you do this please provide screenshots or better yet, the model in max format.