If it is a Series 2 DT, you are pretty well SOL, since it can run only one box at all in its stock condition.
If it is a single tuner, you can easily set it up for cable with box (which is what the cable DTA basically is) on RF in, and satellite box on A/V in.
Series 2 234 Hr Lifetime.
Window XP and Ubuntu Linux on my PCs.
Watching more and more in HD direct now.