Good TV shows usually have one, a muse who weaves his own demented, absurd, and hilarious life into the story line each week. Seinfeld had Larry David, the co-creator and inspiration behind the landmark hit. (He was the alter ego of George, after all.) Then there's Will & Grace, NBC's current breakout sitcom, winner of three Emmy Awards last week, including Best Comedy Series. Who, pray tell, could be the alter ego of Jack, that adorable (if sinfully devilish) gym bunny? That may be Executive Story Editor Jon Kinnally, if his correspondence is any clue. When the director of a religious organization dedicated to helping homosexuals turn straight wrote to complain that Will & Grace was offensive, for example, Kinnally's response was as naughty as Jack could ever hope to be.