dunno, its a chipmunk port, not sure if box2d is also...guess not.
basically you have to set up a space
set the masslesforce for the space.
add a rigidbody which has a shape to the space. and draw all in the onenterframe loop.
btw rigidbody can have multiple shapes.
if i am not mistaking search for "hello world" glaze example in the forums or goolge, should come in handy to.