Bingo. Now we're on the same page. Without the cable box you will only be able to see the analog channels. The terminal does do the digital to analog convertion. Odds are that the cable company only sends out the signal for certain channels out digitally, which is why you can't see them. You must have the terminal hooked up to the pc.
Now your origional question. There is no legal, or illegal ways, that I'm aware of to descramble those channels with the setup you're looking for. Odd's are you will need an IR Blaster . There is a chance that you can hook up a serial connection to your cable terminal and control the channel changes via software. Look on the back of your terminal, if there is a 9 pin serial port there, you could go that route.
Last option: This may or may work for you depending how much you want your system to do. Get a programmable remote and set it up so that the number and channel change keys send codes to your cable terminal, and the other buttons control your pc... > Don't need any control cables that way
[Edited on 17/11/2004 by xar256]