Sorry no, I dont have XM radio so Im not able to do any development with it. If someone would like to donate one I would be happy to work on it.
I have looked into regular FM radio integration, but all of the computer FM radio cards that I have used, get terrible reception, including the built in one on my Mega 615.
I have used amplified antennaes, line amplifiers with no success. I can listen to the radio through my head unit anyway so I didnt pursue it further.