Use your ohm meter. It is a simple pair of switches, right side is battery, left is alternator field. Wire to the normally open contacts. There are more contacts on the back, but it is easy to ohm them out.
Bob Nuckolls AeroElectric connection has all sorts of examples of wiring diagrams (he calls them Z_ diagrams). The book cost $, but he has a free Z8 diagram that may answer your question located at http://www.aeroelectric.com/articles/allelect.pdf
Print a copy and you will see the switch in question near the center of the page.