I don’t believe we talk too much about that in Teemu’s interview, but what we do talk about is developing dwps form, which you will need for this experiment. So I would watch that first and try get comfortable with the dwps anchoring setup and picking motion.
For rest stroke specifically, you can check out the Joscho interview — the rest stroke is a big part of Gypsy technique. You can also check out Chapter 22 of the Cascade seminar, where we talk about using rest strokes for playing pentatonic licks. That might be most detailed description of the technique that we have done.
You can definitely do rest strokes with upward pickslanting, and you can try that afterward if you want. Eventually, you may not need to use the rest stroke, or at least not think about it. This is really just an experiment to help you get the feel for the linear picking movement used for faster playing.