Thanks Philly,
So, to wire a humbucker in series (i.e. as a humbucker)
North start (red) goes to hot
North finish (green) goes to South start (white)*
South Finish (black) goes to ground.
*That's how a BKP comes out of the box: green & white taped together.
To split a humbucker, you switch the green/white to ground (effectively grounding south start, so that north is the only coil switched in)
But if I wanted to wire a humbucker in parallel I'd need to get:
North start (red) AND South start (white) go to hot
North finish (green) AND South finish (black) go to ground
Correct?