It seems that you want to make a connection from PlayIt Live to another location (say a remote studio) and have PlayIt Live take the output of that studio.
While this is potentially possible (you may be able to find a stream encoding client with a built in server and some hardware devices (like Barix) will do this as far as I know, personally I would run an Icecast server at one or other end (a Raspberry Pi would do it).
The tricky bit is making this secure.
You could install Icecast on the source machine
http://icecast.org/download/ for the Windows version then assuming PlayIt Live can "see" the source machine it can pull the stream.
The key issue to consider is security. You would want something considerably more secure than port forwarding (which in my view is a bad idea anyway) to make this work. A VPN would be OK if correctly configured.
Alternatively what about http://www.caster.fm/ ?
Source Connect Now may be worth a try
Does anyone know if its possible to and how to Route A Stream over the internet without out it going into a server first (if that makes any sense) into Playit Live