Don't believe you would need it at speeds above 20 mph. The locker is supposed to be used for low speed applications; thus the 20 mph unlock. It might cause damage to the rear locker, which from my experience reading forums, means the person will remove the bypass and hit GM for the warranty.
We already have enough legitimate hits on warranty for the front axle...
and that is GM's fault.
So, even though I know how, I won't say how.