Jack, I have a few pics on my blog on how I laid it out. Scroll down to the building the hatch lips..
http://kayaksimpledesign.blogspot.com/2012/11/building-hatch-retainerslips.html

Question 1: Fiberglass doesn't like to go around 90 degree angles. To enable the fiberglass to go around the sacrifical gasket you need to have a fillet (I mixed in graphite during this step) on each side of the sacrifical gasket. I used a plastic spoon to make the fillet radius: its like caulking a bathroom tub, but with a bigger radius. The purpose of the sacrifical gasket is to create a recess in your fiberglass hatch lip to enable flush mounting hatches that is leak free when you install the final/permanent gasket.

Sacrifical Gasket: It's hard to see in the pics, but the sacrifical gasket goes on the hatch side and is place it right to the edge of the hatch.
(Remember you laid contact paper as a mold release, so you are really placing the sacifical gasket on the contact paper outlining the hatch)

Question 2: So first, get your gasket material. For me a got 1/2 inch wide and a 1/4 inch thick rubberized gasket material for the sacrifical gasket. For the final gasket, I used 1/2 inch wide and 3/8 inch thick. (The final gasket needs to be a thicker material due to the compression of the gasket during securing the hatch cover.) To hold the hatch, the hatch lip needs a 1/2 inch gap for the gasket width plus I added another 1/2 inch as additional retainer. So on the inside of the hatch opening you will see 1 inch of the hatch lip. You need another 1 inch width to glue to the deck. My final trimmed hatch lip part needs to be at least 2 inches in width; therefore, I will make my fiberglass strips 3 inches wide. (I used the rubberized gasket material at Lowes in the weather stripping section. The final gasket material was only available in 1 inch wide, so I split it into to get it to 1/2 inch width.)

Note- Gasket Jig: To split the gasket material, cut two blocks of 2x4 pine four inches long. Dado out two of the blocks to the width and thickness of the gasket material (50% thick on each block). Insert a razor blade on one of the blocks with a taper angle to split the width of the dado. Feed the gasket material one end of the block to start, and clamp the blocks and rip out as many feet of gasket material as needed.

From here, just center the fiberglass strips over the sacrifical gasket with the thicken epoxy fillet installed (still wet). In building the fiberglass hatch lip, I recommend to lay 4 oz fiberglass strips at 6 times around the hatch at least. I used scrap bias cut strips, especially on the acute curves on your hatch. I cut various fiberglass strips from 4 inches to 12 inches. If you have tight radius on your hatch you may need shorter. Also my final layer of fiberglass I used my longest and bias strips to reduced the overlaps and improve appearance, even though know one would ever see the bottom of this part after installation unless they could turn there head 180 degrees......In looking at the One Ocean website from the previous response, you will notice that they added a plastic sheet and a bag of sand to compress all the layers of fiberglass. Be careful when doing this, look underneath to make sure your tape on the hatch didn't move....

When you first pull the part off the deck and mold release, the hatch lip looks ugly; but, after you trim and sand it looks like a factory part.
This is one of the times if you make mistake here, you are only out a few bucks for contact paper, scrap fiberglass/epoxy, and gasket material. You'll have the opportunity to do it again!

If you buy One Ocean Kayak manual, it has better pics and explains the process better than I can in this forum.

K.Greer Good building!