Hello, I just purchased a guitar that I am building in to basically a JEM. I've ordered the correct Dimarzio pickups but when looking at the wiring diagrams I ran in to a problem. Apparently they have some really odd double pole switch. I have never seen this before. The pickup configuration and function looks to be the same as my S670. Neck humbucker, neck coil split and middle, middle, middle and bridge coil split and bridge humbucker. So, why the special switch? I found them but they are like $50. What is the purpose of the special switch if it functions the same as a standard 5 way? I can't find an answer so I figured I would come here to ask.

Yeah man those switches are definitely expensive. You can achieve the same thing with a fender super switch though. They're normally around $20. Unless you're set on making it officially like a jem. You wouldn't hear a difference with the fender switch. Really any switch that allows you to auto coil split will work. Even a 540s switch

I can coil tap using a regular 5 way. Ibanez has been doing that for years.