2D accelerometer calibration

Hi Everyone,
I am using the accelerometer for movement in my 2d side scrolling shooter and while I have movement working, I can't seem to get it to calibrate based on a position other than holding it flat.
I have checked out the Unity tutorial that converts the example space shooter to a mobile device but that code just doesn't seem to work for me(maybe its because i expect the player to hold the phone horizontally and not vertically).
Any help or advice would be greatly appreciated.
Thanks.