Assuming the doors are static parts of the mesh, several possibilities come to mind. Most involve modeling, but if you don't have access to or skills in a 3D Modeling program, you might check a good tutorial on using the grouping tool in poser. Create a group by selecting the polys of the door you want to open, then make that group invisible (conversly you can use a transmap to do the same thing, but I find the grouping tools easier). Use another simple prop of appropriate shape to simulate a swinging or sliding door. Hope this was useful . . .