I am months late on this, I know, but if you're still out there, hear me out.
The G940 most likely uses a Melexis MLX90333 on the stick - the same sensor that the Thrustmaster T.16000-M and Warthog use, as well as the Saitek
X-55/X-56. All of them have a single magnet waving over the sensor.
However, it interfaces using SPI and requires a ridiculously expensive programmer to even set up for use (thankfully, Logitech
has fulfilled that part for you already). While RealSimulator may have figured out the protocol just fine (the FSSB R3 can optionally have a Warthog stick PCB added for TARGET compatibility), it is NOT something that most hobbyist controller boards and firmwares like MMJoy2 are set up for. Those tend to expect pure analog output from a potentiometer or Hall sensor, not some serial digital protocol.
Even then, you have another issue with the G940: MMJoy2 isn't set up for FFB at all, so how are you going to drive the motors acting on the stick? Even then, you'd have to support the DirectInput FFB API specifically if you want it to work in something like DCS or Rise of Flight.
Alas, I have no G940 to sell you. I sold mine years ago after finding out first hand how cheaply built it was. All I can suggest there is to keep your eyes peeled on eBay.