or run without the power wire and use the internal pullup jumper on the MS board
and the coil wiring for spark control
Or my favorite, how it's wired in the full wiring diagram and two wires to the pickup coil in the distributor (grey line to pin#24)
It IS written in a way over complicated manner. That is because MegaSquirt is designed to be very flexible and work on dang near anything. For our simple old engines:
You only need two wires to control timing. Pin#24 is the tach signal in from the points, pick up coil, crank trigger, etc. Then Pin #36 goes to the negative side of the ignition coil to control dwell and spark timing. Done. Make sure the jumpers on the MS board are set up for the input you are using (just stick with the VR input, it handles practically anything), and set your coil dwell to 2.5ms and you'll be golden.
The 7 and 8 pin modules just add extra wires and an extra module.