The answer to your question is YES!!!!!
You can add SiriusXM radio to your navigation system. I ordered mine from Crutchfield and had no problems with installing it.
The part#(s) are:
113CASR20V----- Kenwood CA-SR20V $19.99
607SCC1---------SiriusConnect SC-C1 $59.99
You will have to go with Sirius as a services provider rather than XM. They used to make a part for the system that recieved the XM signal, but I looked everywhere and couldn't find it (no longer in production).
In about 2 hrs. you can have satellite radio AND navi. for $70
(just watch out for those nasty screws that hold the head unit in)
(I lost 3 of them trying to secure it during installation)