Sounds like you have the right idea! However, make sure that you do not put the Dicor Lap Sealant under the new skylight. Instead, put butyl tape between the skylight and the roof.
X2
I would add don't use any brand sealant in place of the butyl tape.
If the butyl tape job is done right and the screw heads are sealed there will be no water leaks. A lap sealant is just the second line of defense against water intrusion. Pay close attention to a good seal on all screw heads in the roof as this is generally where water has a straight line into wood or the units interior.
Use the you tube and google function and pay attention to how the pro shops or the product mfg do it. The product websites usually have very good you tube's on how its done ...the right way.
