This really isn’t something easily done. Particularly if you want true synchronization. Different clients buffer at different rates, and I think it would take significant client support to be able to synchronize two clients — that is, if you really want them exactly synchronized, like for moving room to room and having the music being seamless.
If you just want close, then you can do something like parsing the log output for song play events and drop it into a m3u and rescan, or feed it to shoutcast or something.
I think if “close” is close enough, I’d do the second option — would only take a bit of perl, and would be close enough.