The reliable method I use for going from O2 → Modo/Max/Maya is…

1) http://www.storiamilitare.org/o2/dw/p2ms.zip The output being milkshape files.
2) Import the .ms3d files into http://www.sharecg.com/v/5169/software-and-tools/LithUnwrap---Free-UV-Mapper-for-Windows and then export to .obj format.

Armored_Sheep (BIS developer): Reset XForm in MAX before you export to 3DS. Check size of your object, too tiny or too large meshes might be broken after import.