I'm not sure if this helps, but bumpmaps are already exportable with v4 exporter(not sure if v3 too) and if i recall correctly they get rendered as flat textures(diffuse) ingame, so that should mean that the engine does actually recognize the presence of this extra texture but doesnt know how to handle it exactly... i might be wrong though, havent quite messed with these things in a while
Diegorborges about my Valo fix: "Now all of you must have your slrr folder like this: C:/BIGBOSSisMYlordANDiamHISbitch/SLRR LOL"