The simplest install is a Cruise Commander in each engine. Not so simple is use three Cruise Ms and a single radio board. John has created a board to make that possible as it boosts serial data. You might also have to replace the tethers to ten pins for the added serial data and direction signals.
A big advantage of the latter setup is all three engines will run in synchrony, especially if you tie all the pickup rollers together with one of the tether wires.
Pete
