OK since this rabbit is still running here goes.
You hook the coil to one spark plug like normal, BUT no ground.
Then you hook the ground wire to the OTHER spark plug terminal.
If you ground the engine to the ignition ground only the first plug sparks
IT works this way, remember that electricty actualy flows from - to +, the spark voltage is sent to the first plug. It jumps the gap and then the voltage is in the engine where it jumps to the sensor and everything burns up and the engine stops. OOPS wrong way.
The voltage goes to the second plug ground electrode where it jumps to the center of the second plug and returns to the ignition as a completed path.
P.S a CH ignition only weighs 3oz.