"I'm having trouble importing a Wavefront OBJ file into Poser 6."

I should have asked what the source of your obj file is.  That might be an issue as well.  A few months ago I stumbled into the observation that both Hexagon and Silo create bloated obj files, especially Hexagon (up to 50 times the size that the obj file 'should' be).  However, in Hexagons case there is an easy work around and Hex gives you a nice lean obj file:  save the file in Hex format first, then export as obj.  Don't know of a work around for bloated obj files created by Silo.

edit:  ...oh.  And don't forget to check that it's not just a scaling issue ;)