Here you can see the side profile of the lockset for this sliding pocket door. I needed about 3/4" of a mortise about 5/8" deep for the lock to work properly. I first outlined where the lock should go and then penciled my lines on the door. To ensure that the drilling would not cause any blow out I used my Olfa Razor Blade to score the rectangular outline before I drilled anything.
With two spade bits I went back and forth until I was deep enough.