I’ve been working on thumping for a few months now. Victor Wooten’s bass videos cover the mechanics. Tosin’s example with triplets is something i learned to do all over the neck. The trick is to get the double-thump going. Where the upstroke happens the same way an escaping upstroke happens with d slant alt picking. The wrist needs to stay relaxed and the thumb is held firm yet elastic. My hand usually assumes the “hang ten” shape, and it’s a similar motion if you’ve seen it before.
The thumb edge has to follow of the same rules as the pick. I sometimes do economy picking style rakes with my thumb. I think about slant and string escape in the same way.
The other thing to keep in mind with this style is that you’ll need to mix in other types of attacks- hammers and string smacks- to really get things to groove.
I also studied Wilco Johnson’s pickless approach during this time and started combining the double thump for basslines with an outward strike from the nails for chord stabs. Similar to clawhammer banjo.
I’m on the lookout for Reggie’s instructional video.