You would wire it the same as the diagram I posted but instead of interrupting the charge wire you would interrupt either of the field wires. (SOMEONE ELSE NEEDS TO JUMP IN HERE AS I DON'T HAVE EXPERIENCE WITH A TWO WIRE FIELD ALT BUT.... as understand one of the wires provides voltage to the field and the other provides ground to the field DON'T QUOTE ME ON THAT!)
You could test out my theory by disconnecting one of the field wires while the engine is running and the alt is hooked up in stock fashion if the car voltage goes from 14 ish to 12 ish indicating no charging, also the amp meter should read large discharge.