I had some time to test a PSC01 today and there is a instantaneous off command after you remove the contact closure. That is, you just momentarily short the two contact posts and the "on" command is immediately followed by an "off" command. I think with what you are trying to do, a standard wall toggle switch would be the best bet. As far is size, the PSC01 would not fit in a J-Box. You would need to run a dry contact wire down to an outlet where the PSC01 is plugged in.

Bill
www.homeautomationnet.com