Make Accelerometer 45 Degrees

This is what I have so far

 var accelerator : Vector3 = Input.acceleration;
 var t2 : float = accelerator.x;
             accelerator.x = -accelerator.y;
             //accelerator.y = (accelerator.y + 0.5) * 2;
             accelerator.y = t2;

how can I make it so that rather than holding the phone flat to make it drive straight, I hold it at a 45 degree angle to drive straight?