Assuming that the impedance and voltage output is the same for each coil, parallel should be OK. I am guessing that the two coils are bascially the same but one gets two poles and the other gets three. If the coils are different, series and the hum cancelling phenomia are going to be compromised as well.
You can also wire each pickup internally in series or in parallel. The default wiring scheme in the Dimarzio instructions is internally in series.
Then you can of course hook up a series/parallel switch for the neck and bridge pickup. A basic V/V/T layout with three push/pull pots: internal series/parallel switching for each pickup on the volume controls and neck+bridge series/parallel switching on the tone pot.
I've done that and the results are phenominal! Although I think that the standard wiring scheme in the pickup is parallel. The pickups sounded hotter and fatter after I installed the mod.
