[Hypnotic2010]

Here is a couple options for you.
1-If you would like to completely disable ALL gsensor functionality you can navigate to HKLM/DRIVERS/BUILT IN/GSENSOR/AND delete gsensor.dll.,

I would suggest to take the following approach:
This method will allow you to switch the screen orientation by holding send button:
1) Change your registry to enable screen rotation:
HKLM - System - GDI - Rotation - HideOrientationUI (Change from 1 to 0)

2) Then, simply map your phone button long press to the rotation tweak:
Settings -> Buttons -> Map with <Rotate Screen>

3) When you would like to rotate your screen, just hold your Phone button.