You can use your thumb and wrist which is how most of the greats do it. It just takes a lot longer to get down.
or you can flip your hand over and use your pointer and middle fingers alternating to push the stick down.
I generally use moller though.
And lastly you can use one handed rolls.
stick is at 90. arm at zero.
throw the bead of the stick down for the first hit.
your hand should be at a downward angle and u should let the stick come back up to 90.
the key is to not choke the stick and stay relaxed.
the second stroke happens during a combination of your fingers and your wrist coming back to the starting point.
Utilize your thumb to get a little more power and control in the strokes.
some other things that i learned from marching snare for 6 years and using traditional grip is....
-when ur holding the stick ur thumb should be resting on the 1st knuckle of ur 1st finger (that forms the folcrum or balance point on the stick)
-the stick should be resting on ur ring fingers fingernail
-when u hold the stick there shouldnt be any gaps inbetween ur ur fingers (it should look almost like ur flipping someone off only dont extend ur middle finger out have it slightly curved, resting naturally on the stick)
-if sumone was to pour water on the top of ur hand it shouldnt be able to collect water in the palm (if it could collect water, then ur hand is open to much)
-and when ur playing with this technique dont have a death grip on the stick ur middle finger, ring finger, and pinky are mainly there to control the stick so u should have a lose grip with those fingers and let the stick rebound naturally