The easiest way by far would be to use a pi rather than a standard desktop. It just so happens that I am also building a flight simulator and am doing so with the pi 2. It also happens that the pi zero has been recently released, convenient if you do not want to make a large investment. The raspberry pi can run a simple python or C++ function to test the input, and even provide outputs. In my opinion a Pi would be infinitely easier to use as this is the type of thing that it was designed for.
Tell me more about your project, which language are you using? How advanced are you within this language? What previous experience do you have working with you language? To what extent are you building this cockpit? What types of inputs and outputs are you thinking of utilising?
Is this part of a competition or an individual project?
Thanks,