My brother has trained both of his Siamese cats to use the toilet. He uses a system similar to the CitiKitty one, where you cover the toilet bowl with a removable kitty litter tray so the cat gets used to the positioning it needs to use over the bowl. Eventually you get rid of the litter portion and the cat simply uses the toilet.
Obviously it takes a little time, so you have to be patient. Also you will have to remove the litter portion if and when you need to use that toilet yourself. But I have seen the cats do it, so I know for a fact it is not a myth!
Neither of them know how to flush, but his toilet does not have a handle for that, so I don't blame the cats
