I started installing one in my car a couple years ago, after I saw Mark's at the COTA rally in 2016. One more project I had to put on hold until I got more pressing stuff done first. When I get it finished, I'll post a how-to.
Mark has the electronic remote control mounted on the edge of his steering hub, so he can reach it with his thumb when his hands are on the wheel. I put mine there too. You have to order the wireless remote control separately. It takes a CR2032 battery.