I just finished building this pickguard using 3 Hot Rails pickups.
The pickups are wired using 3-pin Molex connectors: red for signal, black for ground, and yellow for the coil-split (technically combined) cable. The coil-split cables are wired to individual switches, allowing you to toggle each pickup between single-coil and humbucker modes. This is done by grounding the coil-split (finish of north and start of south) cable, which essentially disables the humbucker behavior.
The toggle button acts as a bridge pickup override. When toggled, it activates the bridge pickup in parallel. For example, in the standard Strat position 1 (neck only), the button transforms the sound to resemble position 2 (neck + bridge). In position 2 (neck + middle), the button adds the bridge pickup, resulting in a combination of all three pickups (neck + middle + bridge).
Initially, I considered using a Freeway switch, but it’s quite costly and limits you to a preset selection of options. For instance, you can’t have the middle pickup in humbucker mode alone. Using a standard 5-way switch with 3 flip switches and 1 toggle button for the bridge pickup seems to be the ultimate solution. Alternatively, I also considered combining a Freeway switch with a push-pull pot for the second tone control, but the cost would be astronomical.