We often get questions about splitting 2 Humbucker to single coil with either a single push/pull pot or with a DPDT toggle switch. Here is a basic module to do so.
1) This is shown as if the push/pull pot were upside down, the way you will be wiring it IRL. This way, you get the split when pulled, normal HB when down.
2) I have used Seynour Duncan wire colors; color codes may have to be adapted for other pickup brands. The white wire is shown as gray for visibility. The red/white pair from one HB goes to one side of the switch, the red/white pair from the other goes to the other side.
3) This splits one HB to the screw coil and the other to the slug coil, so that you get hum-cancellation in position 3. This assume the pickups are identical; if not, some changes may need to be made.
4) If you want to split to a specific coil for each HB (i. e., split the neck to screw coil specifically), this may need to be changed so as to swap the "hot" and "ground" wires around. Likewise, if you want to split to both inner coils or both outer coils- which may also involve rotating one of the HBs 180°, depending on your pickups.
"Gotta buy a tank and an aeroplane When she catches up with me won't be no time to explain . . ." (non-PC lyrics courtesy of Pete Townsend)