Use X-Plane on the computer (Mac, Windows, or Linux,) - which, by the way, you really should use. It's still actively developed, and is way better than FSX (I've owned both since version 1 of each.)
Then buy "X-Plane REMOTE" from the iTunes Store for your iOS device. You can use your iOS device's accelerometer to act as yoke (controller for you non-pilots,) as well as show you various display elements (various parts of your instrument panel, maps, etc.
I do not know of any way to make it work with Microsoft Flight Sim, though.
P.S. There are versions of X-Plane for the iPhone and iPad!
edit: Oh, here are the directions on how to use a
WiiMote in Windows. No 'hacking' required on the WiiMote, but you
do need Bluetooth on the Windows system.