You are correct. Get it lined up and squared away so each side is an equal distance from a referance point on the fuse. Once you are satisfied with the alignment, take a felt tip magic marker or similiar and mark the fuse line on the bottom of the stab. Cut the covering just inside the line you just marked and epoxy the stab on. I assume that you have the wing mounted and zeroed. That will help with checking the incidence of the stab.

Vince