If you want the
inner coils of the pickups in positions 1 and 5, just wire the push-pull-switch to connect the tap wire of each pickup to ground when it's pulled. This will be similar to the regular JS diagram, an shouldn't affect middle pickup functionality in positions 2,3 and 4. I don't know which pickups you have in your RG, so I can't give you the color codes.
If you want the outer coils, check answer #5 and the follow-ups in this thread.
http://www.jemsite.com/forums/showthread.php?t=29209
I wired one guitar like this way, so it gives me a switching like this:
1: Bridge PU, Bridge coil
2: Bridge PU, Bridge coil + Middle
3: Middle
4: Neck PU, Neck coil + Middle
5: Neck PU, Neck coil
Have fun soldering and let's know how it turns out!
