Have you tried the General Instrument codes? Wikipedia notes that General Instrument is a division of Motorola, and somebody noted on a thread here that most Motorola cable boxes (though I dunno if it also applies to their satellite boxes) are basically rebranded GI boxes.

I'm wondering about this problem myself since I also got a 42" Aquos and Comcast digital cable. I stumbled upon the GI suggestion on here after doing some searching, so I haven't tried it yet, but it's worth a shot.