The answer will depend on what other options you have implemented or plan for the CEC run device. If you are not using or plan to use the stand alone signal analyzer with a second nano, then it should be just a mater of configuring the CEC software as if it were the analog S meter interface. I have not done this, so would assume that you can adjust the calibration of the display via the configuration or memory manager software from KD8CEC.
If you plan to use the stand along analyzer, then it would be a little more involved. I do not have an answer for that at this time.
Please verify the above before making plans or changes, as I am going from memory and have not looked at this for a long period (for me) of time.