I hope I'm not annoying anyone with these. Its just what I do.

We did this to my boy's Bullet Strat using the original pups. Sounds killer in all positions.
This came out better than expected, and its real simple:
Replace the 5-way with a 3-way. Replace the 2nd tone control with a simple DPDT on-on switch and make it master vol/tone. (A push-pull pot would work equally as well.)
Switch "down" gives you parallel mode. Switch "up" gives you series mode, for three virtual humbuckers. The switch-up, middle position is particularly cool. Neck and bridge in parallel, and then those two in series with the middle.
Works good, sounds great.
Artie