I haven't been able to figure it out if you can. In order to see the music and actually play it (where it's not grayed out and unclickable) I have to set my music to be manually managed on my PC at home, then I need to get the iTunes library key from the file at home and inject it into the right spot in the same file on any other PC I want to listen to the music on.

I actually just stopped putting music on my iPhone because it was too much of a hassle to do every time that key changed. I just use Pandora or GrooveShark now instead.