Transform gestures

I'd like to, for instance, make a gesture like pinch/zoom or 3 finger up/down trigger 2 finger scroll + modifier key. Adding this capability would allow all kinds of powerful things (like holding down a modifier key to enable one finger scrolling). All we would need is a set of triggers that takes the incoming action values and maps them onto various gestures (2,3,4 finger swipes in all directions plus pinch would be a great start).