if i wanna put a dpdt switch to knock my pups out of phase do i need to solder a ground to the neck pup?
Going back to the original question, I was wondering what your existing pickups are?
All pickups have a ground wire, but if it's a humbucker or P-90 with a single conductor plus braided shield, the braid is grounding the pickup coils
and the metal parts of the pickup. So you
can't just swap the ground and hot connections to put the pickup out of phase with the guitar's other pickup.
If you want to use a phase switch as pagan7 has described, one of the pickups needs to have (at least) two conductors plus a separate shield/ground wire. In practice, that means one pickup will be 4-conductor, although the green and white wires won't be needed for phase switching.