I’ve been working with my stix using my thumb and index to pivot and the others to toggle the stick. I’ve been doing a routine on leg or with a pillow (something without bounce back) where I practice with each finger tapping once and then two and then three times trying to keep my arms and writs loose. It’s difficult because my arms naturally want to tighten to grip the stix. And drumming doesn’t really work well that way.
I’ll be practicing this for the rest of my days. But I should be greatly improved at it in a mouth or two.