Since the SimVimCockpit v.0.9.39 the encoder processing algorithm was fully reworked.
For proper “acceleration” you don’t need to try to rotate the encoder momentary very quickly. You need to rotate it fairly “steady”, the speed of acceleration depends on the “continuity” of movement.
The program checks each X-Plane frame, and if there was a change (or several changes) in the previous frame, it adds more increments, depending on the sum of all previous uninterrupted changes. This gives more realistic behavior than rotating an encoder with quick, short "jerks".
How to assign one encoder for two parameters and switch them with a button (either external or built in the encoder):
In this example the encoder is connected to the inputs #0,1 of the multiplexer on the pin #8. The encoder switch is connected to Mux input #2.