The easiest solution would be RadioFeed
. This has a web server / stream server built in, saving you the hassle of running a seperate mp3 streaming server, like Icecast.
Since it is a server, you would have to open up whichever port you chose in your router and/or modem depending on your set-up.
You are also allowed to set the maximum listeners, probably 1 in your case. Any app on your phone capable of opening up a mp3 stream by directing inputting a url should work fine.