I'll preface this with: I'm not a modder, I'm out of touch, feel free to point and laugh.
I've searched through the old threads on editing MTW images, and it seems like generating the image files is a bit of a hassle. Would there be any point in creating an import/export plugin for BIF/BUF formats for GIMP? There is an LBM plugin (for Linux anyway, source code available, still looking for a Win binary) out there, so there is a start point. I've got the basics of the BIF format, but I'm sure there are some quirks I'm missing. Would this be useful, or are people satisfied with the current editing technique?