And here's how Joe does it:
http://slideplayer.com/slide/4536727/
Or you can take the route I took and convert your 3-rail engines to 2-rail by removing the center rollers and electronics, and installing Battery-Powered, Remote-Control. Of course I had a 3-rail system, pulled up the center rail, and kept all the 3-rail wheels on my equipment (except the middle rollers).
Cost...probably about what Joe asks for a conversion.