Robert McKee talks about seeing himself in Adaptation over here. (Would've embedded it but I couldn't see how.) Here's a little texty excerpt:

Question: What was it like seeing yourself as a character in the film "Adaptation?"

Robert McKee: I took my son to a screening at Sony.  And it's one thing... I've seen myself on screen many times because I've done umpteen TV series when I lived in England and interviews on TV, so it's not surprising, even though I myself played myself in another movie called, “20 Dates.”  And so it wasn't that big a thing to see Brian Cox do me.  But imagine what it would be like for a son to see his father portrayed in a major motion picture.  And so he came out of the screening and I said, “Paul, what did you think?”  And he said, “Dad, he nailed you.” 

Thanks to David for the link!

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