For streaming, you have 2 options, and which works best depends on your needs.
1. Use the built-in VLC integration in Stereo Tool. You can stream directly from Stereo Tool if you have VLC installed on your system. See
http://help.stereotool.com/7.50/sound_cards.shtml and search for VLC in the output sound card settings.
Warning: Something that I've noticed recently: The MP3 encoder in VLC is pretty bad. If you want to stream in a format like OGG this solution works fine though.
2. Use VB Cable or VAC (Virtual Audio Cable).
These are programs with which you can send audio from Stereo Tool to another program, which can be any program that you want to use to stream.
Now, there's a problem here (one that I'm planning to fix, but it's still on my todo list): If you output your audio to 2 different sound cards (VB Cable/Virtual Cable is seen as a separate sound card in this case), the sample rate will not match perfectly. which will cause one of the buffers to get empty.
If you have a sound card which supports virtual cables internallly (such as all ESI sound cards, I'm certain that the ESI Juli@ has it, not 100% sure about others) then that fixes the problem.
Otherwise you could run 2 Stereo Tool instances simultaneously, one for FM and the other for streaming. The CPU load needed for streaming is a lot lower than that for FM so this is probably not going to be a problem.