If you made the model originally and you're more familiar with 3DS than Poser's grouping tool, you could also try chopping out the moveable parts in 3DS & importing separately. Then you could position them in Poser, parent them to the main mesh, and set them up to pivot as you want (you may need to move the origins to make them move properly). This is the method I've used to make prop doors pivot as around a hinge in a prop doorframe. Another, probably better method is in the excellent tutorial at SAMS3D (see Link) it tells you how to make an OBJ poseable (you can export the prop as an OBJ, if needed)