For those who are still reading....here are two nice web sites that explain the whole gizmo to those who do not have a masters degree in automotive engineering ;-)

http://www.aatap.com/

and

http://auto.howstuffworks.com/camshaft6.htm

And no I have not asked if the "smart valves" could possibly be fitted for the Xfire engine.
I think BMW had a really good explanation on their site for VANOS but I think this will do :-D