Nope, an 8bit greyscale BMP as bumpmap exports OK, looks OK in Alchemy Viewer, but CTDs the game.
I did try using the textureviewer to get an MUA bumpmap out, then reinsert it, but whatever format they are in MUA, it doesnt seem to be any of the DXT formats I can save as, as reinserting in the normal "strip the header and reinsert via hex editor" just gets you a messed up skin, even if you alter nothing.
Let me fiddle about some more, then if I fail, and if you are OK with it I'll email or upload a file and see if you can convert it.
(and thanks for the pic references, appreciate it.)