The first step to attaching the skeg is building one. I just used 3/4" douglass fir and cut it to a shape that fit the boats profile and was pleasing to my eye. the next step was too drill a few holes in the hull the length of the skeg. Then have someone hold the skeg against a straight edge while screwing and gluing it in from underneath. This is much easier than it sounds.
Then, just like in previous steps putty and fiberglass it in with the fiberglass tape.
Now, If I were to do it again I would have made the Skeg 3-4" deep. That is my only regret in building the boat.