UVmapper works only on alias wavefront .obj format models. Just about any mesh modeling program available will output this format or it's easy to find a free converter. UVmapper only works outside Bryce. Bryce won't use plugins that I know of. Bryce primatives won't export. The only things that do export from bryce are terrains and the imported objects and meshes. boulean operations don't export. You can use two cubes from imported materials stretch one into a wall and make it positive, Stick the other in the side and make it negative, click the edit button and check the make solid when boulean rendering. If you group these things together you will have a wall with a window in it in bryce. If you export this group and open it in another program you will see two cubes with one stuck in the other. The resizing will apply but the boulean function won't. You can export these as objects and use uvmapper on them to create a surface map but you're stuck with the original shapes that were imported into bryce in the first place. The only thing you can affect is the X,Y, Z scaling.