I'm in the same situation. I've got a 4 gang in my shop w/ standard type switch on it, and I want to change one of them to a decora style wifi. I came across the faceplate linked here, but unfortunately the one I need to change is one of the middle ones, and that box is so stuffed full of wires it'd be a supreme hassle to re-locate all the switches. So, I'm just going to put in the wifi and then replace the other ones from standard switch to decora style switch....either way looking forward to the ability to control shop lights w/o having to run back in there to turn them off.
Also, one more note, is to put your phone up to the switch, and if you don't have at least 65% or so wireless reception on your phone, you may need to consider relocating your wireless router or adding in an extender. I'm going to have to do that as the switch is in the far end of the shop, and only gets 1 bar worth of wifi signal from my house' router which is in the basement on the other end of the house...