I don't know which model Catalina you have, but on mine, the CATV/OTA amplifier switch is located just above the television. Yours should be near the TV as well.
However, rracer says that any splitter in the circuit will prevent it from working with satellite, and nobody else has posted to counter that. Usually, when somebody is in error, somebody will post the correct information. Anyway, if you have a TV hookup in the living room and a TV hookup in the bedroom, you'll have a splitter in the circuit. If you only have the living room hookup, it might still work.
At this point, I'd say you're probably better off simply running your coax directly to the TV as you are planning on doing. Messing with the switch box is only going to delay you getting to watch TV.
2014 Coachmen Catalina 253RKS
2016 Keystone Summerland Mini 1750RD
2012 F250 Lariat 6.2L Crew Cab FX4
Reese dual cam SC/WDH