Hey Davemon, I would like to do the same thing. Right now all I have is standard audio out with RCA jacks. This output can be controlled with my cable remote which briefly displays an on-screen bar graph.
The best I can offer is hope. The cable TV companies are coming under increased pressure to add HDTV, and ultimately digital TV, to their services. When this happens, they will have to give us new boxes. Hopefully (and this is my wish list!) these new boxes will have component color out, options for HDTV, 1080i and 480p, and of course digital audio out. Even if the digital audio out is only 16/44.1 it will be a vast improvement.
If this is more than a few years down the road, many of us will continue to switch to satellite. However, I feel the cable people will respond before then.
A side note: has anyone ever wondered how good CATV or satellite could be if someone like Pass Labs, Krell, Levinson, Accuphase, Sony or EAD made a high-end cable TV box? I am sure many of us would shell out the extra bucks!