#1
Hi, does anyone have a wiring diagram for 3 humbuckers, 3 way switch, 2 volume, 2 tone? thanks in advance!
#2
If you're just doubling two pickups for one of the volume & tone knobs, there's no need for a new diagram, just use a standard LP type diagram and slap the extra pickup wires in with another. If you want something else you'll have to specify.
#3
Closest thing I got for you is this: http://www.guitarelectronics.com/product/WDUHHH3T2201/WDU-HHH3T22-01.html

This has 3 volumes but it could easily be modded depending what you need. The essential problem with HHH wiring and a 3 way switch is two of the pickups, usually middle and neck, can never be separated.
Gibson RD Silverburst w/ Lace Dissonant Aggressors (SOLD)
Electra Omega Prime Ceruse
Fender Franken-Jag Bass

Amps and the like:
Laney VH100R
Seismic Luke 2x12
Dunlop 105Q Wah
Gojira FX 808
Line 6 M9
#4
Assuming you mean the classic Gibson 3-pickup arrangement (Les Paul Custom; SG Custom; etc.), then here you go:



You can just ignore the "push-pull switch" addition in this diagram, unless you want one.
"Maybe this world is another planet's hell?" - Aldous Huxley