Well, I'm surprised that I couldn't find anything online about it. I mean, how hard can it get? An expression pedal is just a pot with a pedal, isn't it? If I were to solder the 3 leads of an expression pedal to a jack to plug in an expression pedal, wouldn't this work? I see this as a really simple mod, with the hardest part being drilling the hole for the jack. In fact, then I would probably wire it in series with the original pot, and get a dummy jack to bypass it when I want to use the pot instead, or turn the pot to bypass when I want to use the expression. Am I very wrong here?