All you need to do to log the position is to know the Y values from start to finish in the meter area and translate those values to your reading value. Then you just grab the current Y value (assuming X is constant) with Pointer.Y stored in instance variable that you compare with your actual values.. ie Y for meter = 100-300 you could output using Pointer.Y = <50 text = POWER: 100% or whatever...
If your meter was exactly 100 pixels tall (or wide.. using X instead) it would be easy to translate to a 1-100% value to post to player (or show on meter) using (gulp) math... say you use Y pixel value 200-300 you could simply assign the Pointer.Y to a variable and subtract 200 for a 1-100% value... etc otherwise you would need to use complex math or a long series of value = result = value conditions.
You could use a SINE behavior to make the pointer actually move up and down and use stop SINE behavior to make it stop at any point you choose.