the best i can think of the top of my head would be to wire the two humbuckers just like a PRS so you had master volume and tone for those. then have a simple on/off switch between the volume and the jack. Then treat the single coil seperately, send it to its own volume and possible another tone and have another on/off switch between that and the jack.
i dont know enough about the rotary switches to work out how to get seperate volumes and on/off switches for each humbucker but it might be possible :?
i think its a bit tempting to go for a complex wiring scheme when putting your first guitar together but it will probably be better if you go for something simple that you know will work.
personally with a 3 pickup set-up like this i would go for a normal fender 5 -way switch but i might put a neck adder switch in to get all 3 pickups together and bridge and neck settings and i might be tempted to add a series/split/parallel switch to the humbuckers for full/half/quarter power.
thats still farily complex - but its easy to get it to work