I'm not aware of that function. It sounds dangerous to me. I can see myself forgetting that I have it on, or off, and doing a lot of damage real fast.
One trick that somebody told me may help you.
Find one edge, and plug that position into G54.
Then find the opposite edge and plug that position into the Operator's coordinates.
Now, go to the screen that shows all four coordinate sets, and jog until the Operator's coordinate and the G54 coordinate are showing the same number. That only happens at the center of the part.
P.S. I just use a calculator.