Um. OK. I have misunderstood your situation a little.
You can indeed have iTunes to list firefly and play from it. You can use your iPhone as remote control. (If it simply skips songs, etc)
However, each client can listen to it’s own music using 1 firefly server.
The fact is, firefly starts a thread for each song requested. It doesn’t go like “currently the server is playing this song” like shoutcast has for example.
So you cannot remote control the music played by one client using another client. (At least, that’s what I understood you wanted to do)
Next to that. There is no client that works with firefly for windowsmobile that I know of. Yet?
Hope this helps.. 🙂