Use the 3ds Export from Moi for have separated objects by groups in Sketshup ;)
You can always load free V6 here for have the import 3DS
http://www.brothersoft.com/downloads/sketchup.html

And why not use the OBJ export from Moi?
here an free obj import with material for Sketchup by TIG ;)
http://forums.sketchucation.com/viewtopic.php?t=20584