Controlling game vehicle engine sounds out of software

I was asked about the possibility of using external hardware to control the sounds of an in-game vehicle engine without playing the game and I'm intersted in whether it could be done.

More specifically, there will be a button for ignition and plane throttle controls with sensors attached (potentiometer most likely) that when pushed or pulled will control the sounds of the engine from in game (FSX) without having the game played.

At first I guessed it wouldn't work but I figured some research might prove me wrong. Google hasn't helped but it is a rather specific request so any advise would be appreciated.

It's easy for an Arduino to read those sensors and send that information to a PC. The real question is how does the game make the sounds and can they be controlled by means outside the game. That's not really an Arduino question and surely depends on the particular game in question and the code that runs it.