Electrical wiring question about Capacitors and Potentiometers with Bartolini NTMB

Hello fellow bass enthusiasts! I have a somewhat complicated question (I think!) about my Bartolini NTMB onboard preamp. I have here the web address of the Bartolini web page showing the wiring diagram from the preamp system: http://www.bartolini.net/instructions/electronics/ntmb/ntmb.htm. Specifically, I am curious about the DPTT on-on-on switch for the mid frequency tone control. The diagram shows that the switch selects between three different capacitor values which, in turn, control the frequency at which the mid control acts on. I understand that there is a difference between capacitance and resistance, but I do not understand what that difference is exactly. Here is the exact question: If I were to remove this DPTT switch and install a 50k linear taper potentiometer in its place with a .5 mfd capacitor coming off of one of the posts, would I be creating "semi-parametric" control for the mid boost? I have an EMG BQC system on one of my other basses (here is the web page: Link Removed) , and the frequency at which the mid is boosted/cut is controlled by another potentiometer. If I boost the mid all the way and sweep the frequency control back and forth while I play, I get a Wah-Wah like effect (listen to "The Patient" by Tool at the beginning of the song. Justin Chancellor has this feature on his Wal bass). I want this feature on my Bartolini NTMB because the preamp sounds better and can be used with passive pickups (the EMG requires active pickups to work). I understand that the potentiometer is increasing resistance as I work it, but would putting a capacitor in line create variable capacitance? Thanks for anyone's help with this ahead of time.

I guess I will contact Bartolini and ask them. I will post the answer they give me here.

I called Bartolini and did not get the answer I wanted. I got no answer at all. He said he wasn't that technically oriented. I did post another thread that was less specific. I asked if anybody new how to make variable capacitance and most replied that preamps with a parametric-like eq use electronics to simulate variable capacitance.