Man, I am presented with the same problem. The only device I can't control with my 990 remote is my Cambridge Audio D500SE. I tried doing that thing with the remote where you search for a code, but you have no idea how long to keep doing it. You wonder, have you reached the end of the codes built in? Just keep pushing, pushing....zzzzz.
Wish I knew of a code that worked.
Shotgun, did you ever find one?