So, I just got my trainer USB cord, and it worked great with my E-Flite transmitter, just had to set up the axes in the KeyBindings.
Can those of you having trouble with the real transmitters give me more information about what you are using? (ie Transmitter brand and number and trainer cord info).
You won't be able to plug a spectrum transmitter into the audio jack, as that requires a lot of code to turn the OSC signals into useful information in game.
Also, @wrobel221, I am happy to have some help with the project, but currently I'm just doing it as a hobby to get a useful training application for quadcopters. I don't have much experience with things like remote repositories to collaborate with others, but if this gets a bit more traction I'm sure I will be able to use the help.