So, you're saying open up the stick, and literally bypass the twisty pot with the wires from the pedals? As if it's all part of the same unit?
I think my skills are up to that level but I have no soldering iron. I'd also be unsure which wires to use from the gameport of the pedals to hotwire them into the circuit board of the stick.
Also, these pedals each move independently. I don't honestly know how this works in-game, as I can't get them running. They don't have a bar with a central pivot. My guess is it averages out the input of both (i.e. both fully depressed = centered. 1 fully depressed, other 1/2 depressed means it's only 25% depressed on the full pedal -- something like that).