A DIY steering wheel controller with potentiometer connected to Arduino Leonardo or other ATmega32u4 based device. This is just a personal project but hopefully can serve as a further example/reference to add potentiometer functionality for others in their projects. Also, this project was tested for Windows, not sure about MacOS or Linux.
Upload the sketch into your Arduino Leonardo (or other ATmega32u4 based devices). Wire Potentiometer to Arduino's A0
This uses the ArduinoJoystickLibrary and this tutorial