I will describe the trick doing it in a clockwise fashion. Start off by doing the Idle. When the devilstick is tossed to the right handstick, hit the devilstick just under the centerline, like you were going to do a propeller. Bring the left handstick to the right, toward the center of your body. Now you want to have the right hand bring the devilstick up around the outside of the left handstick. Let the devilstick then roll over the left handstick. Once the devilstick leaves the right handstick, bring your right hand back to catch the devilstick when it rolls over the left handstick. You can then go right into the the same trick.
This is similar to the saw, except the devilstick is in a plane parallel to your body, rather than perpendicular. Also, the handsticks are on the same side, so you need to take one out of the plane of the devilstick and bring it back around to the other side.
Once you get the hang of this trick try to keep your left handstick virtually still, keeping it in the center of your body. Then just use the right handstick to keep the devilstick going around the outside and rolling over the left handstick. Also, you will want to work on doing this trick both ways (CW and CCW).