Probably quite some musicians who have been working with the computer, one time or another, have a midi-controller lying around somewhere.
With a freeware program, its possible to translate midi commands to keyboard functions, which enables you to put your midi-controller to good use with your flightsim.

I myself got the Peavey pc1600x and so far I've been able to assign the buttons and the rotary control. I'm still working on the faders, but from what I read, those also should be usable in this fashion.

For the rotary control I had to use 000-001 range, for the rest it was all very straight forward.

For anyone who wants to give it a go, here's a link to the program:

http://www.bome.com/products/miditranslator/overview/classic

Have fun!