Above is the 3EQ Sabre schematic you need.
I think you'll have a hard time changing your pickup wiring. Your bridge pickup (two coils) only has two leadouts. It would have to be modified in itself to be able to select only one of those coils. A guitar tech may be able to work it all out for you.
The closest to what you want is the V3 Sabre Classic (2013) which places the bridge pickup at position 5. Again, it would need modification to be able to select only one of those coils. Additionally, a two-wafer switch is used.
V2 Early EB Sabre:
1 Neck pickup, both coils
2 Both pickups, both coils
3 Bridge pickup, both coils (Stingray)
4 One coil of neck pickup + both coils of bridge pickup
5 One coil of neck pickup only
V3 Classic Sabre:
1 Neck pickup, both coils
2 One coil of neck pickup only
3 Both pickups, both coils
4 One coil of neck pickup + both coils of bridge pickup
5 Bridge pickup, both coils (Stingray)