The plot thickens. I just tried loading a gile[s] lightmapped level to test, and that worked. So clearly multitexturing does work (since the lightmap is a multiply-blended layer over the main texture) if I load a b3d file with the multitexturing already setup. Either I am doing something wrong in my code (please double check what I posted) or there is a bug in setting up multitexturing with new textures.