Lean a ladder against or near the roof, close to the Velux skylight.
Tie a rope around a bucket. Put a pry bar, a claw hammer, a screw gun, a heat gun, a putty knife, a roll of ice and water seal, hand roller, a utility knife and roofing nails into the bucket.
Climb the ladder holding the rope, then pull the bucket of tools and materials up to you on the roof.
Remove the shingles around the Velux skylight with a pry bar and claw hammer.
Remove the flashing from around the Velux skylight with a screw gun, then warm the tar around the roof fixture with a heat gun. Scrape up the softened tar with a putty knife.
Pull the backing off the roll of ice and water seal, exposing the adhesive. Lay the ice and water seal around the Velux skylight, then press down with a hand roller and cut off excess with a utility knife.
Reattach the flashing with a screw gun, then replace the shingles, tacking them to the roof with roofing nails and a hammer.