It doesn't quite work like that. The satellite box only outputs one channel at a time, so you still have to change channels on the sat box. It's kind of like digital cable--the stream is encrypted and isn't compatible with just plugging in to a regular cable tuner.

I have a capture card plugged in to the satellite box already, and I've tried streaming TV, but the issue remains that you can't change the channel. I'd need some kind of program that could go over the network to my desktop, and from there issue commands to the box via an IR adapter or something. I've not found anything like that.