McRecipes
I found this interesting collection of McDonalds Do-It-Yourself McDonald's Restaurant Recipes (PDF), apparently based on the production methods of the 50s, 60s and 70s - ie, the unhealthy "original" stuff!
I don't know how authentic it is, but it's plausible - from some of the wording it seems the original author worked for McDonalds in some capacity.
I doubt I'd be able to find all the right ingredients for the "Special Sauce" here in Australia - it's hard enough finding some ingredients for Asian recipes even at the big Asian supermarket.