Just sharing some knowledge, pls find correspondence between me and the helpfull Mr Tim below. :P
Me:
...[I just bought a NailBomb] bridge with 4 conductor. This is going in a custom guitar body which only has a bridge pickup, and there is gunna be 1 push/pull pot for vol and a coil split. And, as luck would have it, there is a nice wiring diagram in the box exactly for this purpose. I will mount the pickup with the screw poles nearest the brdge as suggested. My, question: in the supplied wiring diagram, when in split mode won't it be the slug poles that are active and not the screw poles? I find this a bit counter intuitive since I thought the screw poles where supposed to be adjustable so it would be better if they were active when in single coil mode?
Tim's reponse:
it's pretty much standard protocol for the slug coil to be active in coils split although with 4 con wiring you can effectively choose either coil. Most players prefer the slug coil as it's closer to the neck and so sounds alot warmer than the screw coil which can sound very bright on it's own.