I suspected it was infrared. They encode signals is quite differently from PWM-based radio systems. At least the ones I have dissected did. So, you would need to confront at least two major obstacles.
First, there is no place to pick up signals for the stick positions that will easily be converted to what is needed for the simulators. In fact, it is likely only one of the three IR controls is proportional. Simulators will need both sticks to be proportional.
Second, I am not aware of a three channel simulator. All of the modern ones use at least four channels to control pitch, roll, yaw, and throttle.
I suspect it would be easier to build a control box from scratch than to convert an IR box to control a simulator.
John