No connections, but go to
http://www.xmradio.com/programming/directory.jsp and there's a list of all their programs. If you click on each, they give you a description of the kind of music on that channel, and there's a place to the left to request a song.
I left requests on Channel 15 (The Village - folk), channel 22 (Mix - adult pop), Channel 23 (The Heart - romance), Channel 24 (Sunny - smooth vocals), Channel 25 (The Blend - singer/songwriters), Channel 26 (XM Live - self explanatory - requested either of the two live cuts), Channel 45 (XM Cafe - soft pop/rock), Channel 50 (The Loft - mellow rock) and Channel 71 (Watercolors - cool/lite jazz - requested No mistake About It).
They ask for your name, email, city/state, artist and song, with a box for comments to the DJ if you want.