Have you checked out the TiVo Community UK Forum? There's some very knowledgable folk in there, and the problems of getting TiVo to talk to set top boxes (including cable boxes) have been discussed many times.
Start here - you'll find various digital cable discussions linked to about half way down:
http://www.tivocommunity.com/tivo-vb...ad.php?t=37326
I use TiVo with our NTL (Pace 2000) box. Although the box has a socket for connected a direct remote control signal, AFAIK it has never been enabled by NTL.