You just need to design a holer for the pot, see pic below. Sorry I lazy. STEP and Fusion Project available below. 

The black spring thing in the middle is an electric fence spring. Dunno if it will be available in your country but try , even any extension spring you can get to work will work.


Then you can use arduino with atmega32u4 to emulate input device and make pedal work in games. You can google that part, but feel free to ask if help needed.