reverend,
There are some Squier wiring diagrams
here, however they don't have one for the Custom or Custom II.
The '72 Custom wiring should provide the same (or nearly the same) functional control as the factory wiring for a Squier Custom. If you have a switch of the same connector orientation as a '72 Custom and want to wire your guitar like the '72 Custom, then the '72 Custom wiring diagram should work. You just need to transpose the wire colors. If you have a switch with a different switching or connector orientation you'll need to transpose that too.
For transposing the wiring colors...
I have a Squier Custom. I have a different set of pickups in it now and its original pickups are in box. I could check mine when I get home, but here's what I would do then so you can just check this yourself.
Buckers like those with only two conductors normally have one of the two leads connected to the cover, as well as to one end of the pickup coil. So you should be able to check with an ohmeter to determine which of the two wires coming from the pickup is connected to the pickup cover. Use that lead as ground, and connect it where the '72 Custom diagram shows the black and bare wire going. Then connect the other lead from the pickup where the '72 Custom diagram shows the brown wire going.