My Comp G doesn't have XM either, but the previous owner installed a part by the name of "aai-gm24", and mounted in aux input on the dash next to the head unit. I push band until the screen actually says XM, and it works. I have the stock 6-disc monsoon.
I'll have to give that a try. It says I may have to go to a dealer and have the unused xm port in my radio activated which is do able. Thanks for all the advice guys!
04 CompG, black HAI, 180*, TR55s, custom tune by me, SD headers soon
04 CompG, fusion orange, all stock
99 GTP, red, coupe, 3.4, SLP exhaust, basic mods, PB 13.56, SOLD in 09.