On mine, the external coax for park cable came into a two coax connector wall plate beneath the TV with a short jumper between the two coax connectors. That brought the external signal into the wall plate and the jumper redirected it to the TV amplifier/switch box. I could remove the jumper and connect a coax cable from one of the coax connectors on the wall plate to the sat receiver box. And the Tailgater and sat receiver box worked fine. I later added a second external coax connector specifically for the sat box.
So, if you have a wall plate with two coax connectors on it and a short coax jumper between the two, you may be able to remove the jumper and attach a new coax cable from one of the coax connectors on the wall plate to the receiver box. If it does not work from the first, try the second.