Before Charlie Kaufman was Charlie freaking Kaufman, he was writing for TV, and one of the shows he worked on was The Dana Carvey Show. Also in the writers' room were Stephen Colbert, Steve Carell and Louis C.K.
There's a new documentary on Hulu about the show--Too Funny To Fail--and while I doubt that Charlie makes an appearance (only his high school year book photo's in the trailer--same one that's on this website), it still might be worth watching. (I have no idea how long it'll be available. I got onto this late and have no clue about Hulu.)
A.V. Club has a good write up on the show and the doco.
How does a sketch show featuring some of comedy’s most brilliant minds become “one of the most spectacular failures in all of television history”? How does a series starring one of the most popular comedians on the planet alienate his fan base so swiftly and decisively that his career never fully recovers? And finally, is there some inversely proportional relationship between complete fiasco and eventual cult worship? These are some of the questions posed by the amusing, appropriately niche Hulu documentary Too Funny To Fail, although the more direct one is this: How did The Dana Carvey Show—arguably the most daring, prescient, talent-stacked sketch comedy to ever hit American network television—become such a massive flop? (Source)