asteel - Well, that depends.
If you have multiple computers each with their own webcam, simply run the iCamSource on each one, using the same login and password on all of them.
If you have multiple webcams on one computer, it depends on what operating system you are running. If you are running Windows, just run a new instance of the iCamSource for each webcam you have, and select a different webcam in each one. If you are running OS X on a Mac, simply make additional copies of the iCamSource program, and run each of them, choosing a different webcam in each one. (OS X won't let you run multiple instances of the same program bundle like Windows does, so that is why you have to make a copy.) If you use the same login and password on all of them, they should all show up in iCam at the same time.
I hope that answers your question.
