Switch the positive.

The +ive coil feed should then be cut through pins 1 on the smaller circuit.

No real need to use the resistor on pin 2. It's there to prevent damaging the alternator by 'sinking' the excess current to earth.

In reality in that split second you'll have fuel pump, ecu fan etc etc running which will do this, so no halm will be done.

Its only really neccesary on older cars which aren't running anything that could sink the current.