The coating on the tongue is something Burroughs mentions briefly in his book, The Master Cleanser, on page 27. He says, "One of the best signals of the completed diet is when the formerly coated and fuzzy tongue is clear pink and clean looking. During the diet it becomes very badly coated."
In case you're interested, here are two links to traditional chinese medicine websites that talk about diagnosing the patient by tongue color and texture.
Before I send you there, I'd like to tell you I've gone through the furry tongue phase on the MC. I decided to do the cleanse until my tongue was pink. It took 20 days. A friend did it and it took him 26. The tongue does get coated with white cheezy stuff as you're detoxing. It does clear up if you continue.