With Disney partner Pixar (”Monsters, Inc.”) and DreamWorks-owned Pacific Data Images (”Shrek”) doing so well, is there room for another major computer-animation player? Fox, who teamed with Blue Sky Studios, certainly hopes so. After the debacle of the hand-drawn ”Titan, A.E.,” execs are banking on the sleek CG look of ”Ice Age” to lift the studio’s ‘toon hex. After Wedge won an Oscar for the 1998 short ”Bunny,” Fox greenlit his feature debut, the story of a woolly mammoth (Romano), a sloth (Leguizamo), and a saber-toothed tiger (Leary) who partner up to return a human infant to his tribe. But getting the narrative to work required some shaping. ”A lot of scrutiny is given to this stuff because of the cost,” says Wedge, who declined to talk budget (industry estimates say it’s at least $75 million). ”The concepts are vetted exhaustively.” For instance, a subplot which found Leguizamo’s sloth cozying up to a couple of females got whittled down to just one scene. ”It was too double entendre-y,” says Leguizamo. ”It was hilarious, but kids weren’t laughing, and parents weren’t either.” Preview audiences seem universally tickled, however, by a mute little ”scrat” — part squirrel, part rat — and its acorn-burying antics.