Well, it turns out it gives you a few sonic options, albeit pretty tame ones:
1) Standard wiring - The usual volume/tone control configuration.
2) Control bypass - This gives you a slightly brighter and louder output.
3) Bass - The signal is run across a relatively high-gauge capacitor to give more of a bass-like tone. Early guitarists used to resort to this option to play bass lines when no actual bass guitar was available.
|How's it done?
The interesting thing about the wiring is that the (formerly pickup) selector switch is wired in "reverse" relative to what most guitarists are used to. Rather than the signal leaving the switch through the common lug, that's where it enters. And instead of selecting between different pickups (since there's only the one), the options are different types of outputs.
I don't know if this is actually how it's wired, but this will achieve the same end (at least as I understand what the guitar is supposed to do).
More importantly, this schematic illustrates how to use a "pickup selector switch" not for selecting pickups, but rather for selecting between tone circuits. This could include pre-amps, varitone switches, other tone knobs, etc. Take this idea and run with it!