I don't know if you're using a toggle or a rocker, but it doesn't matter...the back still looks the same.
Ok, based on the picture below, if "up" was moving the toggle towards A and B, the below connections should work the way you want. If its a rocker switch it would be like tilting the rocker towards A and B.
A: Constant +12V
B: Purple HVAC wire
C: +12V in run to fan controller
D: A/C Demand to fan controller
E: Constant +12V
F: Constant +12V
What this means is that when you move the switch towards terminals A and B, C shorts to E and D shorts to F. When you move the switch the opposite way, C shorts to A and D shorts to B. Any position other than off gives 12V to the fan controller to enable it through terminal C. When you move the switch in the "on" direction you give 12V to the A/C demand line of the controller through the D terminal to force it on, and the "auto" direction just gives it the usual A/C demand signal.