How this pickup is made is kind of like a P bass pickup. It's essentially 2 small single coil pickups, wired series, and mounted right next to each other. I also believe that one is wound opposite the other and that prevents hum (though better experts can clarify that).
They put it together in a way that can't be "rewired" without a lot of trouble, so it just has 2 leads: black and white.
(if yours has a grey wire, it's only to connect the pickup's sheilding to a ground on the bass.)
Pickups like the Dimarzio Jazz pickups can be wired "series" or "parallel" because they are built to allow that. Each of the side-by-side coils has a "+" and "-" lead that can be wired to a switch or fixed permanently as either. BUT... if you did a "split", you'd only end up with 1/2 of the pickup functioning, ala the E and A would work, not the D and G.
If you find a pickup that is humbucking and has 2 coils built like this:
you could wire them with a split because they'd cover the entire span of the strings. But most bass pickups like that are like:
and those won't fit into the cavity you have.
I hope that helps.