Basic serial position command closed loop

I have a controller using a Closed Loop Position Tracking setup with an analog motor control input and an analog feedback sensor that works great. The question is if I wanted to use a serial command from a script to give motor position and not use the current motor control input signal what command would work the best?

Example:

The motor control input is reading 2.0v (<2500 value) but I want to override the signal with a serial command value of center or 2.5v (2500 value) what script command would be best?

Thanks for your help and suggestions.