I'm doing some preliminary research because... well, I'm just that kind of guy.
I'm considering a guitar with 89/SA/89 combo from EMG. Ideally, I would like one switch to put both 89's into single-coil mode. As some of you know, an 89 essentially contains 2 separate pickups in one housing-- an SA single-coil, and a humbucker that is similar to an 85. Even the wiring treats them as separate pickups, and they SHARE the same preamp, meaning that the two pickups within the one housing/casing can never be used in combination. (or, the pickup can't be used in combination with itself, if that makes more sense)
Switching them between modes individually is trivial. But EMG assures me that there's "no way" to 'split' (not really split, but I'll use that term henceforth) both pickups at the same time with the same switch. I suspect they just haven't considered all the possible switches out there and are assuming that people will only have access to or will only purchase a DPDT switch (or use one on a push/pull knob). I suspect there's SOME way to do it, even if you use an unexpected switching system... for example, an LP 3-way toggle and a strat-style 5-way (or even 4 pole 5 position if needed).
Ideally, though, I'd like it to be a 2-way switch (think of it as humbucker mode, or single-coil mode) and then a 5-way blade. One of the Steinberger original lines had ONE mini-switch to split both coils, but I can't find any literature describing whether they're both split at once, and if it's a 2-position or 3-position switch.
If anybody has any ideas or insight, it'd be appreciated, though in the interest of full disclosure-- I AM primarily just researching the possibilities right now.... more compulsion and curiousity than putting action into motion.
Greg