This is all USX wrist motion with trailing edge grip, very similar to what I’m doing here for the country licks in the middle of this clip:
If you want to try this approach, here’s how to do the grip:
…and here’s how to do the motion:
Just remember that this approach generates USX motion, so you will need to play lines where the final note on every string is an upstroke or a downstroke sweep. Those are your two main options, for the most part. This is the George Benson way.
George will occasionally do a downstroke string change here and there, almost exclusively when he’s moving to a higher string. And I do that too in the country clip, which you can see in slow motion. But the simplest approach is to just try upstroke-switching licks, like 4nps chromatic licks starting on a downstroke, or 2nps pentatonic licks starting on a downstroke. For Benson type players, those two types of phrases are the core of their entire vocabulary. 4nps is probably somewhat easier to start with since you’re not switching strings as often. Try that on two adjacent strings and see if you can get it going.