Or you could just buy a 1" paddle drill bit, and pop two holes on the back of your box, drop in a pair of paralleled NL4MPR connectors, solder the positive and negs together respectively with a chunk of 18-2 or 16-2 cable and just jumper off the positive and neg leads to the 1/4" and you are set. Parts express will have full plate kits, but you may need to mod your cabinets to work with the pre-made plates or vice versa. When I've built or modded boxes, I've always just popped the NL4MPR's in and been done with it. But do check out Parts Express to see if they've got something that will work out of the box. But if you do it the way I am suggesting, you can get your connectors via the net or from a nearby guitar center-ish type store if one exists near you. But with a 1" paddle bit and a handful of 3/4" drywall screws you are done in minutes. But you have to buy the NL4MPR, the round ones, when you sink the square ones straight into the wood, they have a tendency to be less than stable and don't last physically. The MPR version has a larger surface area and handles the stress of being straight into the box much better.
Good Luck!
