I've given up on it. I've got other plans for how to work it out.

See, our setup is a little different. Our primary receiver is in our basement, hooked up to a distribution box that broadcasts the Sat receiver on channel 18 to the TVs in my house. That one has both a "Low" and "High" speed transfer connection on the back, one of which is 9 pins. I'm hoping I can get a new RF receiver to replace that one, and move the old one so that the Tivo can use it.

I'm just hoping that the other box's "Low Speed Data" port is what I'm supposed to be connecting to. I went to Best Buy today, and none of the new receivers have serial connections.