There is a book about this subject it tells how to do it in good detail, lots of pictures. Probably available through Armchair sailor, or Bluewater books. Gugeon brothers also puts out a booklet on this subject. Possibly available through Sail net. Also I recommend adding a thin layer of new wood over the old wood.(cold moulding) This will give a better, clean, fresh layer upon which to attach the glass to. Do NOT use polyester resin use epoxy. The poly resin is not as able to flex as epoxy and cracks. it does not adhere to the wood as well as epoxy, especially to old wood that has been in the water soaking up all sorts of oils and who knows what. When the dry boat is put back into the water and swells the glass, if improperly attached has been known to fall off. Also the old caulking could be taken out and filled with either a wooden spline or epoxy, before the new layer of wood is attached. Small bronze or stainless ring nails and epoxy can be used to attach the new layer. If you do nopt want to spend the money for the special cold moulding veneers sold, then get ceder 2x''s, or the closest type of wood to the type that the boat planking is made of from, and cut it into as thin strips as you can and attach them to the hull. One layer should probably do the job, two or three even better. I found that if you do it vertically (90degrees to the planking) that it is easier. This also will tye all of the planks together and you will not have to worry about a but block letting loose.