It took me approx 700 events to get the physics behaviour to behave the way I wanted it to. Think of it as a 20 mode FSM, with each stage progressively added onto the last, starting with a simple move left/right with appropriate accel/decel profiles, then jump, then land, then crawl, then push/pull another physics object, and so on... It was all done using events to control the player's physics object, stop it from bouncing, move it up/down slopes correctly for the appearance I wanted. A real in-depth and fun project, but it took on a bit of a life of its own - it was good fun to do but, now I've done it, I'm not sure that I'd do it again (I'm drawing up another platformer while I wait for Steam Greenlight, and it will not use phyiscs for the player). It might be easier to use the Chipmunk physics plugin, if you're unfamiliar with both, because that at least permits you to have more access to core physics behaviours and information than the c2 physics port of Box2d does.
Edit: I'm now familiar with the limitations of c2 physics engine, and their are small modifications that can be made to permit kinematic bodies, so I might consider making a personal port of it to work with if I need to.