Transmission/Engine Similarities

How similar are the transmissions and engines of the SVX and the Legacy? I was browsing a Japanese export site (www.takakaira.co.jp) and noticed that they sell a "twin-mode clutch system" (read triptronic) that works in the Legacies. Thing is, I don't know if the key to the system is the engine (which they list as being the EJ20 which we only have in the WRX) or if it is the car's tranny itself. Any clues? Oh, if anyone wants to look at the web site, the product is by 5Zigen.