I don't have a high bandwidth subscription, but here is my technique which I think works well. I am assuming you know the basic idea (hit the string and then lightly touch the string with your thumb directly following the stroke). I always found it hard to "choke up" on the pick while playing fast so what I do is to grab the pick like usual but the stick my thumb farther out over the pick. (I usually grab the pick between the underside of my thumb "knuckle" and the side of my index finger) I then pick the note and use the side of my thumb to touch the string. It gives a nice clear harmonic. It's hard to describe but try what I say and you may figure out what I mean.