Ah... Gotcha. I'd suspect that TV codes (0017, 0016, 0056, 0092, 0463, 0624) would have been the best bet, but (my Zenith HDTV has a built-in ATSC tuner and they may be using the same remote codes for standalone tuners as well), but it sounds like you've tried that.

Remember that the code databases are separate for different device types (CBL/SAT, TV, DVD, VCR, ...) and the device buttons on the remote are configured by default only to look at the "relevant" codes for that device type. You can re-direct a device button to look at a different section of the database, but if you skip that step then a TV code will do nothing useful when entered for a CBL/SAT device button.