I've done this before but with a Delco alternator which only had two prongs.
How I did that one (going by memory) Cable from the battery to the terminal on the back of the alternator. Ground from the Battery to the alternator case. Made a jumper wire from the hot lug on back of alternator to prong 2. Prong 1 would go to a 12v switched source such as a ignition switch or toggle switch.
Your alternator should set up as shown below.
runs to the gen light. (Not used)
simply jumpers over to the stator plug.
runs to a switched 12v source. A wire from battery with toggle switch will work fine.
Batt lug to Battery +
Ground to case.
I've read of two different ways to wire this. If above does not work, Run a jumper from the Batt terminal on back to alternator to A. Run your switched 12v power to I and S jumper to S.