Exporting to ETO, MAW, Rising Sun mods is just the same as to vanilla CFS3.
Exporting to Gmax from 3ds Max needs the BFF-2007 script from
scriptspot. The file has two versions: 0_4_2 (not good) and 0_4_3 which is the one to use: copy it to your 3ds Max 8\Scripts folder and run it. You can now make a custom button in Max (right-click on a toolbar) for the tool - you'll find it in Category:
Bobo_s Tools. Drag the tool name
BFF_Exporter to the toolbar and you'll have a labelled button ready to use.
Load your model and click the button. A dialogue pops up and you'll save yourself grief by unticking
Animation - they don't export reliably. You can also speed things up by unticking
Materials. When you click on EXPORT SCENE you'll be prompted for where to save this: make a new folder somewhere convenient because there can be a lot of files written to subfolders. A lot!
The progress bars on the dialog start chuntering through the job. When it's done, fire up Gmax and run the script saved to the new folder. Gmax will reset after prompting and to clear the workspace and the script will rebuild the model in Gmax piece by piece as it works through all the files in the subfolders. This can take a while.
When finished, zoom in and behold your imported work. Check the UV mappings: they're still there, as are all the object names and the hierarchy, pivots are correctly aligned etc.
A few notes! Don't try to export a 200,000 poly monster in one go: either Max or Gmax will fall over as the script eats up memory. Materials can be awkward if not very simple: the script doesn't like .PSD or Mental Ray shenanigans and Gmax will cough: .BMP or JPG iirc work okay.
You now have the work of rebuilding animations, assigning materials or making them visible in the viewport - the dreaded blue & white chequered button - and getting ready for CFS3 export. Have fun!