Voice Chat with Shoutcast

[projexis]

I would like to setup a form of voice chat using Shoutcast (because the audio quality on Yahoo Messenger / NetMeeting is so dreadful).

Can this be done by running multiple instances of Shoutcast on the same machine with different ports, or do I have to put them on different machines.

Assume that both parties are behind routers / firewalls, but there is administrator access to only one them