Finally cracked how to broadcast into SL. After downloading various packages which internet searching suggested would help the solution came via a chat with the guy who runs the Hummingbird Café in SL.
There will be a test today. I will be online much of today (Monday 26th February). If you can come into SL, send an IM to Luzo Orbit and I'll tell you how to listen.
If you can't make it into SL and want to try out listening in the old-fashioned way, send an email to email@example.com and I'll tell you what to do.