Thanks for your response. As you see from my other post, I already found the solution myself, but it never hurts to have this stuff down for the sake of some hypothetical googler having the same problem someday. Or for compiling a howto...
The suggestion to look at the source of READ-BITMAP-FILE, in particular, was nice. I didn't know that existed. Your example also was interesting, although my problem was with one-bit pixmaps specifically. This is a handy mailing list! -- | Dan Knapp, Knight of the Random Seed | http://brain.mics.net/~dankna/ | ONES WHO DOES NOT HAVE TRIFORCE CAN'T GO IN.
