I have set up BigPondTV RTSP streams in MC here in Oz.
Got around it by doing the following...
Change the "rtsp://" to http://
Once playing, import the stream to your library and tag the media Type "Video" and Sub-Type "TV Show".
Tag the Series as, say, IPTV.
Create a new Library Item in Tools > Options > Theater View with the rule Series = "IPTV"
Nest the item under "Television"
It's not completely integrated with TV Functionality (Can't assign channel numbers etc) but works for now...