Anyway, open your model in gmax/Renx and then run the gmax2obj script (included). This will fill the listener window in the bottom left hand corner with a whole load of numbers. Now open the GmaxSLGrab exe file (also included). This takes the contents of the listener window and saves it as an xml file. Find the file and change the extension from xml to obj. Import in 3ds. SUCCESS!
Note: This method results in the unhiding of all objects in the open file. Also, when reading, the different objects will all be combined, so for some objects 'exploding' them before export is useful (eg. tanks, drag the turret up, the barrels and tracks away from the body etc.) so that the objects can then be detached again. Also, don't export with textures. You may be able to save the uvw in Renx and then reapply it in 3ds but I haven't tried (not that good with skinning, so what I just wrote may be complete rubbish...)
Anyway, hope this helps...