Go to the website of the broadcast. There will be a link for beginning the broadcast, usually labeled "Listen now", or "Tune in now". Hold the control key while mouse clicking on this link, and select Copy Link in the contextual menu. Paste (command v) that link into the Processing field in the Processing pane of the WireTap Pro Session.
Click on that link and allow it to load as intended.
If the stream opens in RealPlayer, go to the Play menu in Real Player to Show Clip Source and you can copy the URL from the information window that comes up.
If the stream opens in Windows Media Player go to the File menu to Open URL...and copy the URL listed.
If the stream opens in iTunes, then it is a bit more difficult to obtain the URL. Go to the File menu to Get Info and the URL will be listed, but it can not be selected and copied.