This trick combines the saw with the variation on the saw. So you will need to be able to do the saw in both positions (knuckles up and knuckles down). After you know how to do both, it is a matter of mixing them in a certain pattern while doing the saw. I will go through the hand positions for each hit of the handsticks.
Start in in the saw position, holding the handsticks in the middle, both handstick with knuckles up. All of the rollovers with the hand knuckles up will be made on the front of the handstick. And all of the rollovers with the knuckles down will be on the backside of the handstick.
The devilstick will roll over the right handstick (knuckles up), then roll over the left handstick (knuckles up). While the devilstick is rolling over the left handstick, turn your right handstick so that the next hit with it will be knuckles down. The devilstick will roll over the right handstick (knuckles down), then roll over the left handstick (knuckles up). Turn the right handstick back over so the next hit will be knuckles up. The devilstick rolls over the right handstick (knuckles up), then roll it over the left handstick knuckles DOWN. The next hit will be right handstick knuckles up, this is back to the beginning of the pattern. If you keep this pattern going continuously it looks real nice. I also have a little notation for the pattern below.
All of the above can be described with the following notation:
LKU - left knuckles up
LKD - left knuckles down
RKU - right knuckles up
RKD - right knuckles down
Here is the pattern:
RKU, LKU, RKD, LKU, RKU, LKD, (back to beginning of pattern)