The fueltech has a programmable mixture table table to be used with a throttle position sensor(TPS) which is simply a potentiometer. So simply mount a potentiometer, tell the fueltech it is a TPS, and adjust the TPS mixture adjustment map to your liking. There you have a manual mixture knob.
In fact, the EC-2's Control board returns the voltage of its 5K ohm potentiometer so I hope to simply use that one which is already mounted.
It is also possible to use the micro switches in the EC2's control module to activate almost anything you want through the fueltech.
Dave Leonard