Has anyone bought the XM module for a Non-Nav equipped HCHII? I'm wondering exactly what is included in the kit. I want to know if it has a separate antenna, or if the HCHII already has an XM antenna waiting to be plugged in. I'm using a Samsung Helix XM unit that I'm very happy with, but I would like to tap into the exterior XM antenna, if there is actually one built in to the car.