wiring up three pickups?

You could have a blend for 2 pickups and then another blend to mix the first 2 with the 3rd. You'll see this arrangement sometimes on a bass with two pickups and piezos.

You could wire a 5 way like a strat and then have a push pull pot give you just the outside 2.

1 pan pot for the outside 2 and a switch to bring in the middle.

You could treat 2 pickups as you would the 2 coils in a humbucker and have a series/parallel/single switch and blend that with the 3rd coil.

You could also get a rotary switch and really get complex.

Here's one that just goes for 3 volumes.
[Invalid or Expired Link Removed]

Have fun

heres how i have my monster set up on my p-bass:

neck and bridge into a 3 way on/off/on dpdt
middle pup is always activated and unaffected by the switch
all 3 pups go into a 2 way series/parallel dpdt switch
all of this then goes into my Noll 4 band preamp w/ 2 way active/passive dpdt switch, not shown

the p pup can be solo'ed at any time when the 3 way is in the middle position but cannot be solo'ed in series mode

i have it this way because even with all the mess i put into it it is still a p bass and i like the tone, everything else is ment to supplement this

i have dimarzios as well, pretty much the same except they are the basic p/j set and the neck is a SD quarter pound single coil. this wiring actually works except for a minor issue which i am sorting out, you might wanna check my thread on that subject

this is a very possible setup and depending on what you want out of your guitar you can wire with a 3 or a 5 way, the series parallel switch is very cool and adds versitility. hope this gives you a little confidence.