Here's another wiring setup using Seymour Duncan Hot Rails pickups (although any SD single coil sized humbuckers should wire the same). If these pickups are installed with the standard Strat switching, positions 2 and 4 give you 2 humbuckers in parallel. With this setup, positions 2 and 4 give you a single coil of one pickup in parallel with a single coil of the other pickup for a sound more like a traditional Strat in-between sound. A north coil of one pickup is combined with a south coil from the other pickup to maintain the hum cancelling properties of the pickups.
In this version, Positions 2 & 4 also have no tone pot in the circuit.
1. Bridge Humbucker
2. Bridge South Coil & Middle North Coil in Parallel - No Tone Control
3. Middle Humbucker
4. Neck North Coil & Middle South Coil in Parallel - No Tone Control
5. Neck Humbucker
Click on the image below for a larger version.