Got the switch today. Here's the pinout for those that are want to know before ordering:
There are five positions, three pins are extant, looking at the back of the switch, from left to right, - A - B C (alpha is a pin, - empty)
"off" - no connections between C, B, or A
RR C is connected to A
FR-RR C is connected to A, B is connected to A, C is connected to B.
My amateur read on this:
C is for 12V in
RR - 12 V out on A
FR-RR 12v out on A and B
Exactly how you'd expect to work. Not sure how or if it dims yet, but testing with a 9v didn't lead to illumination . . . with these pins it is not super likely.
*Edit fix pin refs