You have those directions right on the money. A couple of tips;
It pays to get the precut foam just right b4 trying to glue it. Take an square that is roughly the size you will need, fold it in half (make the crease!) and then cut the two sides at the same time. This will make it easy to match the shape for both sides.
Try to get the bottom seam closed off first when you start the glue. You can always add more inside the 'cavity' to secure the shank. As you get the shank starting to set, push down at the front opening to exaggerate the open shape.
I tried coating mine with a thinned, slow-set epoxy. I bought some Hard-as-nails later but havn't put it to the test. I'd like to hear some comparative feedback if you have tried both?
A question for you? Did you find that the fly sat on it's side in the water? Did it turn upright when you retrieved it? I had called Joe and he said that they will ride sideways when stationary since it's hard to prevent them from getting top-heavy, but they will straighten up when you are stripping....
Aren't his coloring schemes beautiful?