Hi jon,
dunno if you are interested in implementing that particular technology more than having a quick and working solution,
in my experience a much easier way would be using an ultrasonic range finder, sorta like Maxbotix EZ-1,
it gives analog voltage output proportional to the distance of the nearest surface, from 0 to 6 meters,
reasonably cheap and nothing more than plugging 3 wires, the +/- and the analog input.
I've built a sortof theremin just connecting the reported range to the frequency of a sine oscillator in maxmsp,
then you can use the same data to control some phaser-reverb-delay effects giving you much more expressivity.
Hope it helps,
ciao!
gio