the soundbridge does mms streaming, but iTunes doesn’t. In fact, if you put a mms url in iTunes it just chokes on it. So the soundbridge (afaik) won’t use a mms url that get’s sent from iTunes. Only when entered on the radio station slots in the web interface. Kinda lame, but there ya go.
You can use a regular m3u playlist for you other stuff.
— snip: Arizona.m3u —
— snip —
Make .m3u files with paths to the .url files you want on a playlist, as above.