how do you set a 3 postion flap set up an a 9c and adjust the mid points ? []

Simple.

Adjust the linkage so that the servo is centered when the flaps are in their mid position. (usually refered to as takeoff/approach)

Then adjust one end point so they are full up, and the other end point so they are full down (land flaps). If you need to tweak the center position after that you can either re-adjust your linkage or use sub trim.

I second the cuda...........