You can drag-and-drop any Poser file with embedded geometry onto UVmapper, and it will deal with it as if it were an OBJ mesh. It just ignores the non-OBJ bits. However it won't save as a PP2 or whatever, just as OBJ, so you have to import back into Poser and add to the library. When importing, uncheck all the options, and the prop will be the same scale and position as before.