Push and pull knobs? Extra switches?

I had always heard how Jimmy Page modified his guitar to have push and pull knobs for various pickup settings and on songs like Since I've Been Loving You from TSRTS or the official DVD you see him playing with his knobs(Heehee) a lot and his tone constantly changes, especially in the intro. The same goes for Dazed and Confused from Earl's Court when Page is playing the classical Spanish guitar solo.

I noticed something similar when I was in the Seminole Hard Rock Hotel and Casino a few months ago and upon checking out Jeff Beck's guitar I noticed he had two extra switches on his guitar, aside from the casual tone/volume knobs and toggle switch.

With Jeff Beck it's very well known that he doesn't use effects but always sounds like he does, so I am wondering, did Beck and Page modify their guitars' hardware to provide various tones and effects with all these crazy switches and knobs, and is it possible for just anyone to do it for a reasonable price?

They probably just wired the switches into the the pickups, allowing for weird combinations of pickups on multiple pickup guitars. It's not hard at all, if you have a diagram and know how to solder.

You can get some neat stuff, like on a strat you can have all 3 pickups on, or the neck and bridge positon, things like that.

Or put them out of phase to get a weird chime-y effect