Hi Colin, so here's an example for how it will work in the next beta.

You'll click near one corner of the base surface, near one side of it like this for example:



Then on the other surface you click on the equivalent spot where you want that to match up with, so you would click near this spot:



Then that will produce this kind of result:



So you won't click exactly on a corner - you click closer towards the edge nearby the corner to one side of the corner or the other side so there are 8 possible zones.

Anyway then it will swap or flip any UV directions as needed to make the output match those spots up.

- Michael