You might want to try this method instead. I had a wonderful Coconut Porter from Flat Earth Brewing at last year's NHC. They soaked the coconut in vodka for about a week, drained the vodka, mixed it with brown sugar, and boiled the mixture until it was had a gravy-like consistency. The mixture was added toward the end of the boil. Also use White Labs English Ale 002. It's a very flocculant yeast that will leave a hint of sweetness that you'll want.