It takes a while for John Leguizamo to get into sloth.

"I've got to walk around the house a lot the day before, working on the lisp so that it's not too much, that it's just right," he says, demonstrating. Sloths have lisps, or didn't you know? The ancient ground sloths did, as Leguizamo interprets Sid the Sloth in the "Ice Age" animated films. "Sid's a vulnerable character, with a higher-pitched voice than you'd think. So I have to tighten up, get the voice up there so that he doesn't sound like a sloth who's been out partying all night.

"I don't get to work with Ray (Romano) or Denis (Leary, his vocal co-stars in the films). It's just me and a script, not even a picture of what the scene will look like. You create the whole emotion of the character and what he has to do in this scene with your imagination."

Leguizamo, star of one-man stage shows, movies ("Moulin Rouge") and TV, plays one of the most popular characters in the "Ice Age" films, the third of which, "Ice Age: Dawn of the Dinosaurs," opens Wednesday. The secret to the success of "the rambunctiously goofy" (Variety) Sid may not be his open-hearted childishness and clumsiness. Leguizamo thinks demographics play a part.

"Tom Rothman (CEO of Fox Filmed Entertainment) told me that we're the largest portion of the audience for these films - Latins," Leguizamo says, laughing. "My people!"

Leguizamo, who turns 45 at the end of July, marvels at how well the "Ice Age" films have done, at how much the technology that creates their distinctive computer animated look has improved and how the producers keep finding funny things for Sid the Sloth to do.

"They've been sending Sid off on separate little adventures these last two movies. I start out with the group, get rejected, go off on my own and get into trouble. In this one, I come across three dinosaur eggs and I get to represent single moms all over the world!"

Leguizamo laughs.

"He has a biological clock. He's got mothering instincts. Sid's ahead of his time."

The "Ice Age" movies are critic-proof, but Leguizamo still figured out a way to win over his toughest audience - his son and daughter, ages 8 and 9.

"They loved it to death, man. But you know, they're a little biased. They're in it. My son was 'Beaver Boy.' And my daughter was the aardvark."

An actor and comic known for his edge, "Johnny Legs" has roles in the arty new film from the director of "Orlando" (Sally Potter) titled "Rage," and in "Gamers," a thriller built around video games from the creators of the Crank movies. He'll leave the PG world of cartoons further behind on July 10 when he sets off on his latest tour, a one-man show of comedy and autobiographical reflections he's calling "Fugly."

"It's about my career, all the problems I had getting started, fighting the knuckleheads in show business," he says. "And it's going to be funny." MCT