Building a pedal with external expression pedal - switched TRS jack?

[ItsGiusto]

Hey all. I'm about to start a build of a Mad Professor Snow White Autowah clone:
http://tagboardeffects.blogspot.com/2013/04/mad-professor-snow-white-autowah.html
http://4.bp.blogspot.com/--dV3lzyt4Zw/T_xAYx1DuYI/AAAAAAAABuw/gfMLjzLKOV0/s1600/mpswaw.gif

It seems for this pedal that if you turn the Sensitivity all the way down, the pedal acts as a sweep filter, in which the center-point of the sweep is controlled by the bias knob. See 2:30 in this video:
https://youtu.be/pfB4IfmEcyU?t=2m31s

In light of this, I'm considering adding an expression pedal jack that would control the Bias knob. The idea being that I could turn the sensitivity all the way down, and use the expression pedal to actually use this pedal as a wah, instead of an autowah.

So, I'd like to use a jack that will disconnect the bias knob pot and instead use the expression pedal's pot. I know there must be some TRS jack out there that would allow me to do this, but I just have to find it, and I've found surprisingly little info on Google about this, at least with the search terms I've been trying. I was considering the Neutrik NYS212, which claims to be "switched": http://www.rean-connectors.com/en/products/1/4-jacks/nys212
But the problem is, I don't know what the switching schema of the NYS212 is. And I don't want to buy the jack, pay shipping, and wait until it gets here for me to find out it won't work how I want it to.

I think what I want, ideally, is to have a TRS jack that has 6 lugs (two for each tip, ring, and sleeve). When no plug is inserted into the jack, the two tip lugs are electrically connected, the two ring lugs are electrically connected, and the two sleeve lugs are electrically connected. I'd attach each of the lugs from the bias pot to one of each lug for tip, ring, and sleeve, and I'd attach the other corresponding lugs to the circuit. Then, when a plug is inserted, the electrical connection between each of the two lugs for the tip ring and sleeve would break and the circuit-facing lugs would instead be connected to the TRS from the inserted plug, meaning that the bias pot would no longer be connected to the circuit - instead the pot in the expression pedal would be.

Does that make sense? If so, what kind of TRS jack could I get that has that sort of "breaking connection when a plug is inserted" schema? Or if you have alternative suggestions that would allow me to create an expression pedal input, I'm all ears.

[duck_arse]

http://www.taydaelectronics.com/hardware/6-35mm-1-4-plugs-jacks/6-35mm-1-4-stereo-insulated-unswitched-socket-jack.html

there are others at tayda, but this is exactly functional for what you want, normally closed, switched, isolated, stereo jack.

[ItsGiusto]

Thanks, ordered!