I'm trying to install a p-rail bridge pickup in a Epiphone Les Paul Jr. This is a single pickup guitar. I am going to use one stacked volume tone knob and a Gibson style three way switch. I would like to get one position to be the rail PU only, one of the other positions to be the p90 only and i would guess the center position to be both the p90 and rail. I have looked at the wiring diagrams and have not found one like this. I could guess, but I would not like to screw this up. Any help would be greatly appreciated.