I have a portable XM ONYX radio we use in the truck when travelling and then it's transferred to the TT when we stop.
For the TT I added another 12V power outlet for the XM radio (saves the 12V TV outlet.) The XM antenna is snaked out between the slide seals when it's partially open and the puck itself sits on the slide roof. On out previous HTT I had a metal washer and sandwiched the awning between the antenna and washer to hold the antenna in place.
The Jensen in the TT has a mini jack but it's a 3-conductor plug for an iPod(?) w/ video. I picked up a plug & cable that has 3 RCA plugs on it at Target, and another cable w/ RCA connectors to a mini plug. If you go this route it's the "AUX 2" input on the Jensen.
The XM also has an option to use a wireless FM connection to feed the audio radio.