well, just to be clear about things, positions 2 & 4 are actually in phase. musicians like buddy guy who played strats w/ the original 3-way switch found that you could balance the switch in between the main positions for a unique "quack" sound that they started calling "out of phase." this was a misnomer as the PUs are wired in phase. what basically happens is a kind of electro-acoustic phase cancellation due to the proximity of 2 pickups that pick up and transfer the same frequencies.
one way to approximate this would be to cut the 2 coils of the 2 HBs that are farthest away from each other. so, the 2 coils closest to each other would be on. if you have a regular 1-switch coil cut setup, you can turn your HBs around so that the adjustable polepieces are on the bottom in neck poition and on top in bridge position (ala peter green). this is because the coil that is usually cut is the one w/ slugs, leaving the one w/ adjustable poles on. of course, this would limit your coil cut possibilities to that "quack" sound. if you have plenty of switches, you could equip yr guitar so that you can select which coil you want to cut.
the only other possibility that i can think of to get "quack" from HBs is to have a switch that puts the HB in parallel (within itself), thereby turning it into 2 singlecoils. the coils are even closer that strat PUs so i'm sure it could get quite "quacky!"
I really like those parallel options of humbuckers, either two coils from one HB in parallel, or a coil from each pickup. It may or may not quack like a strat and definately not like a duck, but it has a nice twangy sound.
The real opportunity in using HB's cut in this way is to always pick coils combinations which are hum-cancelling. You can find both in-phase and out-of-phase hum cancelling options by picking the right coils. What I think about all this is here, with some circuit ideas: au.geocities.com/guitarcircuits
Here is the basic wiring config for the Humbucker Series/Single/Parallel array you spoke of.
I have done this to a project and it works exceptionally well. Especially with both humbuckers. If both pups are engaged then you have almost an onboard EQ by adjusting the various configs. I use the Neck to add bass (Series) or trim bass (Neck Parallel) or add even some twang (Neck Single) Even in full amp saturation mode, you can hear the difference.
The single configs do not sound exactly like strats, but they have a unique and musical sound, assuming you have good quality, reponsive pups.
I also recommend a slightly hotter pup, since output in Parallel and Single is obviouly less than in Series. Too hot though and you get Muddiness in Series.
The prob with this switch is that you need a DPDT ON.ON.ON, and I have never seen this in a PUsh/Pull --- Only in Minis, or huge reg sized (size of a LP 3-way toggle. So getting to you no appearance alteration requirement adds complexity.
You could replace the 3-way with a large ON.ON.ON, then contol pup being engaged with push/pulls. But that means you contol the Series/Split/Parallel on only one pup.
Ahhhhh, go ahead and whip out the drill. The minis don't take much room, and you need only two, if you do not do the IN/Out of phase config on the Duncan design.