Map Traktor Z2 volume faders to fx?

[jam1chicago]

I would like to map an alternate mapping to the stock functions to my Z2 mixer's volume faders. I'd like to be able to use a preset FX (lets use Streeeeeetch for this example) parameter to be changed by moving the volume fader.

I'd like the volume fader at it's full volume to be the FX at 0% then as I fade it down, increase the FX percentage up to 100%

I'm not new to mapping at all, I just can't figure a way to handle this method using the volume faders. Anyone have some insight? thanks!

[Chaser720]

I'm not on my Z2 but cant you just map the volume fader to the FX knob and invert the control? What's your current attempt at mapping it doing wrong?