You can buy that adapter at Radioshack for like $3...sorry, but I just wanted to make sure everyone knew where to get one. That stuff can be hard to find when you go to Best Buy and say "I need a male RCA to male 1/4"". I can imagine the response from the kid "We don't carry RCA -- we haven't had that in like, a year or something."
Also, if the 1/4" input is stereo compatible (which I'm pretty sure it is), you may need a special mono RCA to stereo 1/4".
Last question, then I'll shut up and mind my own business, but does your satelite radio have more than one RCA output? I would think you'd have two outputs, one for each channel, but maybe I'm missing something (I've never had one myself).
Hope that helps.