For the purposes of this build, it will follow the manner of the movie in how they jump. Obviously, since a specific electromechanical device can "anchor" and reopen a jumpscar, I'm pretty sure it wouldn't qualify as magic in the dresdenverse.
Actually, that's one of the two reasons I picked it. The first reason being that I think the struggle between jumpers and paladins given a noir twist would be good for the d-verse. Therefore the second is that I'm personally looking for something to fit in the game that is superhuman without being magical.
Don't get me wrong, I love the d-verse and especially Harry, but I'm most satisfied when Butters makes his attempts to justify magic with more abstract theories regarding quantum mechanics...mostly because of Michio Kaku's personal expressions that psychic abilities do exist and are perpetuated by the presence of hyperspace. It's of course far from provable, but he believes it, and I think he makes a decent case for it.
But, the main reason I'd prefer their power to be non-magical is really just to screw with the magical entities. It bears mentioning that I'm the type who really gets into the idea of pitting Star Trek vessels vs Star Wars vessels...and things of that nature. I love the "what-if" game. Since magic has already been "what-if"ed into the d-verse by design, it's time for something new.
Besides, unless they actually violate the flow of time (which teleportation from one point in space to another point in space in the same point of time does not do), the law itself has no regard for the physical relationship between space and time. Even if it did, it's not as if the White Council could do anything. Obviously thresholds have no effect on the abilities of jumpers in the movie, and like neither would circles unless made as physical barriers only perhaps.
That said, I had intended on chopping their ability into many small parts and to place a number of restrictions I haven't fully determined yet. High enough refresh costs on their powers could easily explain why so many jumpers "go bad" in the eyes of the paladins.
I'll have to give it some thought though. If anyone else would like to take the idea and run, I'd be happy to collaborate as far as possible, but I personally intend to make it something other than magic.