When browsing through various forums, it becomes evident that a lot of people who do not have the ability to get a joystick (perhaps in their early stages of flight simulation) AND people who have a joystick but there is no available axis to assign for rudder control.
Do not fear! We have a solution just for that. NOTE: This will work for Airbus A318/A319/A320/A321 and most other aircrafts in FSX.