Alright I had the same sort of a problem on my Challenger 37TB. Here is what I posted before:
I had the exact same problem on my Challenger 37TB. Here is what I posted on another thread. Hopefully it will help.
Had a similar dilemma on our coach with a Dish Tailgater. Long story short - there is not a specific connection in my unit (or according to Thor Customer Support) any other Challenger 37TB. The solution is fairly straightforward. You make a connection that comes in through your unit's cable connection by splitting the signal, then putting in an A/B box and a coaxial modulator. This all sounds complex but it really isn't. Just a bit time consuming.
You can read my post on the particulars at Tailgater on Challenger 37TB - iRV2 Forums
I had to do part of this before.