To do that, youll need a 5 way double wafer super switch. Its actually simpler than youd imagine to do that configurations but youll need quite a bit of spare wire. Also youd need to check that the cavity can fit a super switch. (Shame if it cant cos without routing theres not much you can do.) But the wiring for that would be to have the first wafer set up for the regular H-S-H pickup configuration and the second for S-S-S, but dont join the two wafers. Then have the wafers connected to the switch such that in one position it takes the signal of the one wafer and the other position takes the other wafer. Then wire up the rest of the controls normally connecting to the switch's output. The controls need to be after the switch in the signal chain. But itll be a great mod. Best of luck with wiring and have fun.