Is it the VC or the 2d panel that you want to adjust? Believe or not, they require different files.
2d:
Here's how to calibrate the gunsight in the Panel>Panel.cfg file. Here's an example panel.cfg for the Hellcat:
[Views]
VIEW_FORWARD_WINDOWS=%window_title_00%
VIEW_FORWARD_DIR=2.7, 0.0, 0.0 << Modify this line
(verticle), 0.0 (horizontal), 0.0 (fore-aft)
Or
[Default View]
X= 0
Y= 0
SIZE_X=8191
SIZE_Y=4086<<<---Modify this line
VC:
To change the VC zero, go to the aircraft.cfg file:
Scroll down to near the bottom of the cfg file and look for:
[Views]
eyepoint=-4.70,0.0,3.29<< Modify this line
Example: eyepoint=fore-aft, left-right, verticle (Greater # = higher POI)