Re: 3 PU Spin a Split
You can, but it won't quite work the way you think. You'll have one coil of all three pups on all the time, and your selector will select which of the other coils are on. In other words, you'll always have a minimum of 4 coils active.
Thats probably not what you want.
Btw - is this using a standard Fender 5-way? If so, there is another way to get closer to what you want.