I've seen in another thread that you use Wings.

Open your model in Wings and there cut it using "edge loop" and "loop cut" later.
Remember all surfaces which were made by cutting object must have "hole" material. I  forget about it very often. You can "name" parts of your model in wings, or just export as an obj all separate meshes. In Poser you find groups with weird names (cut0004 or sth similar). Anyway you can use them in setup room.