Start by doing the saw in a forward direction. When the devilstick is rolling over the right handstick, stop the devilstick with the left handstick once the devilstick end is at or above your chin. You will need to stop it before the devilstick is in the vertical position (the point where it rolls off the right handstick). At this point the devilstick is going to want to start spinning in the reverse direction. This is where you will need to place the end of the devilstick on your chin. If the devilstick does start to spin in the reverse direction, it should be slow enough to get your chin underneath it. Once it's trapped on your chin, raise the devilstick to a vertical position with your handsticks for balancing.
You can try to balance the devilstick on your chin from a reverse spinning saw. You will not have to stop the spinning devilstick as you had to in the above method. However, I find that the devilstick is always spinning too fast, and you just bludgeon your face with the devilstick.