frankly, you won't do it. I use Poser and Sketchup together as well, and basically, SU cannot handle the Poly counts of the simplest poser figure in any useful fashion. (Eg Posette, the basic Poser 4 human female, she's 40,000 polys, that's without clothes... a Victoria 3 or 4 is 60-90K)
you need to reverse your thinking and go the other way. SU to Poser. it's easy enough with the OBJ export scripts or if you have poserpro, Collada.