This may be a useful starting point for some (of a technically-minded nature):

http://liveonsat.com/rugby_union_int...end_yyyy=2007#

It's not currently listing who is covering next weekend's semi-finals but, as you can see from the coverage of today's two remaining quarter-finals, the list of satellites transmitting the fixtures is pretty extensive (please change the time zone to suit your location).

If you can match a satellite to a TV station you're in business.