Paul
Basically, X10 will work on 240V, 50Hz but it needs to be converted first. There are places that sell the converted modules in UK, Europe, Australia etc, but I dont know about South Africa. Bear in mind that these modules tend to be extremely expensive compared to the prices you see on US websites.
Have a look at these two sites.... the first one is an Australian distributor for X10 who will ship internationally, the second is a site which explains converting the american modules to 240V.
http://www.eon3.com[Link: geocities.com]Cheers, Cammo