If what you're writing is a comic book (or maybe I should say "graphic novel") then some variation on "Aiieee!" will probably do. But if you're writing a story or a novel, you'd probably be better off not trying to spell out a scream but using narrative instead to say the character screamed. Could be my imagination's just limited these days, but I can't think of a way to spell it out that doesn't have that comic balloon feel and that's probably not what you want for prose fiction.
My two cents, for what it's worth.