What do I have to do to get Sirius in the X-Star??

I have an '08 X-Star with the Clarion deck. In the manual, it says that I need a SIR-CL3M CeNET module for the Sirius radio. I did a search for it and didn't come up with anything. I already have the Sirius Sportster deck in my truck, but didn't want to have to keep moving it back and forth from the truck to the boat. What exactly is the CeNET module and where do I go about getting one? Thanks a lot guys.