I've made a few tapped single coils.
I used strat, or tele flatwork, and installed a third eyelet.
Put the start lead in first eyelet, wind and connect your tapped coil to the 2nd middle eyelet.
Then start second outside coil, with start lead in 2nd middle eyelet, wind and connect to 3rd last eyelet.
Connect 3 hookup wires, (Black red, white, or Black yellow, white, etc) to the eyelets, to go to switching.
I never tried it, but some use a blend pot on tapped pickups.
The 3 eyelet method works fine, but will not allow isolated coils.
If you want isolated coils, it would require 4 eyelets, and more elaborate switching.
Also like to add, that the eyelets, make for a cleaner pickup build, than actually tapping inside the coil.
Both will work, but eyelets, IMO look best, and eliminate the possibility of shorts.
**If anyone else would like to add anything to tapped coils, please feel free to jump in!