Its gotta be wired similar to this: toggle goes between bridge and middle. Bridge slide switch reverses phase of bridge pup. Neck slide switch works as normal, turning the neck pp on and reversing the phase of it.
This way you can have all 4 phase possibilities which are: bridge-neck/bridge-middle/neck-middle/bridge-neck-middle/.
I would wire it like this because you cant reverse phase a pickup with a gibson style toggle switch.
