After writing my previous post, it struck me that someone must already have come up with a remote control e-stim device. It’s an obvious idea and of course they do exist. For example, here’s one from the estim company (official site here). It’s a lot more expensive than your average dog shock collar, but it also has a lot more features and should avoid that whole pesky business of frying your nerve endings. With the addition of some suitable attachment straps, I don’t see any reason you couldn’t use it for the same kind of play.
Updated: There’s also this one from ErosTek. Similarly pricey, but looks like a great toy for remote controlled fun.
These two images from the Men are Slaves site shows a couple having fun with what looks like a remote estim.