Icecast - Mar 2008 - Alternative playlist based on referrer URL?

Hello everyone,

   We run a site that streams local police/fire/rescue onto the internet.

   We run a large number of feeds.

   We find that other people on the internet directly link to the feeds, 
and take credit. Some actually collect donations, even though we provide 
the service.

   I would be interested in a setup so there is an "authorized list of 
referrers" .. that is, sites we allow to directly link to us. If the 
client referrer comes from some place else, then an alternative playlist 
is used with a static file that explains that we do not allow outside 
links to the feeds, especially those that take credit for our work. So 
please use the proper website.

   Any suggestions?

 			- Ethan