Assuming you have an uninterrupted run from the out coax connection the the OTA power supply / Cable wall plate, all that's required is to remove the wall plate and disconnect the Cable coax connection. Install that on the single side of an A/B switch and then from the A connection run a coax back to the original connection in the wall plate and then from the B connection run a coax to your satellite receiver. That's it, A gets you cable and B gets you satellite depending upon what you have connected outside. No additional wiring or modifications required.
Hope this helps but assumes that's there is a simple run from the wall plate power supply to the receiver.