two things going on here, 1 the individual pickup, 2 the set of pickups. The most commmon wiring for running two pickups together is parallel.
Now what this thread is talking about is regarding one pickup on its own. A 'bucker has two coils, these can be wired together in series or parellel, the other option is to just use one and split it - which is what your guitar does.
To give more options, you can do many things. Some would require extra switches. I'd think about two push pull pots to give series or parallel switching, with a standard three way.
Hope that helps!