Here's the wiring of the original dual rail pickup. Note that the original pickup is wired in series.
The Seymour Duncan Little 59 can be wired in Series/Parallel using a DPDT mini-toggle switch. The wiring diagram for this configuration and the alternative Series only configuration can be downloaded from the Seymour Duncan support web site at http://www.seymourduncan.com/support/wiring-diagrams/
Note that Seymour Duncan has a different colour coding of pickup wires than the original pickup.
In the following picture you can see the mini-toggle switch installed and partially wired up. The pots have not been replaced and measure 500K.
Here's the Little 59 pickup attached to the metal surround.
Finally a picture with all the connections wired up.
I drilled the hole for the mini-toggle too close to the tone pot. I'd suggest you position it closer to the jack socket.
If you'd like to see some of my other guitars visit http://www.guitars4you.com
The sound of the little 59 is a bit more crisp and even across the frequency range compared to the original dual rail pickup. However it is not a big difference in my opinion. The dual rail has a resistance of 11.7K compared to the 14K of the Seymour Duncan when wired in series making the little 59 somewhat hotter!
When the little 59 is switched to parallel it gives an almost Fender Telecaster reminiscent kind of sound.
