Thanks to Broofa on Tivo and Digital Cable Motorola DCT700 [Text View] - TiVo Community:
"To make a long story short, the Motorola DCT700 is, in fact, manufactured by General Instruments (I got this straight from TiVo tech support). So when walking through the channel changing setup you need to choose "GI" as the manufacturer. Crazy huh??? Especially when there isn't a single indication on the box to that effect. :mad: Anyhow, when all is said and done, I landed on the 00093-C IR code for this, which seems to be working just fine.
Now if that's not enough, the tech support weenie gave me the following codes to try: 10006, 10019, 10032, 10042, and 10046. I played around with those as well and the 10046-B setting seemed to work. Some others probably do as well, but I spent too much time on this as it is."