reacTIVision is a no go for construct2 as it captures motion and turns it into TUIO data
You need a TUIO client
Looking at this TUIO client as a possible plugin adaptation: github.com/fajran/tuiojs
could be nice to have true multitouch in the browser?
The speed concerns me though!!!
Then again you could go native with Cinder (C++), or if you are just getting starting and the code stuff is kind of scary (like me!), try open frameworks openframeworks.cc