This isn't an answer, but I know that third party applications can be developed to play XM audio streams. Maybe this will give someone an idea about how to do it for the N800.

In my office I have speakers connected to the home audio system so I listen to XM via satellite all day long. However, the XM receiver is several rooms away. I got very tired of running through the house to see what that song/band was. My solution is to run a Yahoo! Widget on my desktop called XM Tuner (http://widgets.yahoo.com/gallery/index.php?author=3778)

This little widget is pretty cool in that it acts as a stand alone player for Windows - not a plug in for a web browser or anything. It will play any XM station in low or high bandwidth mode. Or, the way I use it is to select a channel and pause the playback - it still updates the display with the current song/artist, but uses almost no bandwidth or processor cycles.

Not sure how he did it, but maybe it wasn't too hard. Someone much smarter than I am could probably figure it out.