[euhlmann]

In C++ there is a ResetDisplacement function, so I'm surprised it's not in labview. I guess you'll have to define your own offset variables and subtract those from the values.

The only other thing I would say is not to rely on it too much. Since it works from the accelerometer it may be inaccurate, especially if your robot shakes around (eg going over the rough terrain, rock wall, etc), and it will get more and more inaccurate over time (like yaw, hence the reset functions for both in C++).
Definitely don't use it as the only metric for your position. Use rangefinders or image processing to confirm it.