TORONTO

Christopher McCandless' family trusted writer Jon Krakauer to retrace his final steps -- into the wilderness of Alaska where he lived to his fullest before dying at his weakest.

They weren't sure they were ready for someone to tell the story again, on screen. That's why it took Sean Penn a decade to get "Into the Wild" made.

"This was a very raw, fresh wound with the family when the book first came out" in 1996, Penn told the media during the Toronto International Film Festival.

"They felt very appreciative to Jon Krakauer for tracing steps they weren't capable of tracing at that time and answering a lot of questions, but they also felt lightning may only strike once in terms of taking a risk on allowing someone into their tragedy. They needed more time to get to the point where they felt they would have the faith to let a film be made."

They placed their faith in Penn, who directed, wrote and produced the movie (and even met the press in a hotel ballroom that barred smoking).

He cast Emile Hirsch as McCandless, asked Eddie Vedder to write and perform the music and assembled a film family that included actors Marcia Gay Harden, William Hurt, Hal Holbrook, Vince Vaughn, Catherine Keener, Jena Malone and Kristen Stewart.

To play McCandless, Hirsch tapped into a long-ago but vivid memory of a television report about the privileged young man who graduated from college, jettisoned his possessions and disappeared into America.

"I first became aware of Christopher Johnson McCandless when I was watching '20/20' when I was about 8 or 9 years old," Hirsch, now 22, said.

"I just was flipping through the channels and I was struck by this story of a guy with the courage to go into the wild, and when you're a young child, the idea of doing that is unthinkable, or at least it was for me. So it always stuck with me and when I finally read the book years later, after Sean told me to read it, it was like the memory was unearthed."

Shedding 41 pounds from his slight frame was only part of Hirsch's preparation for the role.

He read Jack London books, especially "The Call of the Wild," and Walden's "Thoreau," and engaged in "rigorous, rigorous, rigorous running and hiking and endurance tests." However, it wasn't just a question of how far or long he could run.

"I would pose a lot of mini-challenges to myself: I'm going to clean my entire apartment spotless, and I'm not going to stop until every grain of dust is completely organized, because I had heard when McCandless would start a job, he would finish it."

To finish "Into the Wild," the movie shot two years of weather systems in eight months in 35 locations, with and without beard growth and weight loss for Hirsch.

"We started going to Alaska at the end of spring, so there was still a lot of snow on the ground. We went back four times, so we would leave and come back, leave and come back, and I really grew attached to the bus," which McCandless called home in his final months.

"It was the only location we kept going back to. I went back to the bus more times than I went to my apartment in L.A. The bus became my spot. I loved it."

The abandoned, snow-covered bus was pictured on the book Penn spotted in a California shop. He read it cover to cover the first time and, 10 years later, wrote the first draft without rereading the text. He revisited it when polishing the script.

As it turned out, he had remembered it perfectly. "Jon Krakauer's book was masterfully written in the first place and so each reader's interpretation, though different, was certainly indelible."

It had been Hirsch's work in such movies as "The Lords of Dogtown," "Imaginary Heroes" and, later, "Alpha Dog," that impressed Penn. Hirsh also will be seen in the live-action "Speed Racer," one of the movies that will kick off summer 2008 at the box office.

"I wasn't very familiar with the actors of Emile's age," Penn acknowledged. "Frankly, what I was familiar with, and this might be just the embittered older generation looking back at the youngsters, I felt that generally there was a shared weightlessness to most of what I was seeing. Some clever guys and girls. Some sexy, some not. Some charismatic, some charming, some funny but nobody that moved me, nobody that gave me great hope in the future."

Until Hirsch, who also fulfilled Penn's desire to "photograph somebody on the cusp of boy to man."

For much of the movie, Hirsch wore a gold watch McCandless had given to Jim Gallien, a union electrician headed for Anchorage. Gallien, who picked up the youthful hitchhiker and worried he was ill-prepared for his adventure, plays himself at the film's beginning.

While Hirsch obviously could not meet the young man he portrayed, some of the other actors accepted or rejected that chance.

Hurt, who played Chris's father, opted not to, while Harden talked with Chris's mother and Malone met Chris's sister, Carine, who shared stories, journals and letters that helped to shape the movie.

"So much of it had come from her, as a woman, from things she had written when she was younger or conversations Sean had had with her," Malone said. "It's so funny. I had a little bit of sort of a pause before meeting her because I knew, like, wow, this is the first time I ever met a real human being I'm going to portray," Malone said.

Her job, she suggested, was to "do the subtraction" and imagine Carine as a 16-year-old. "That was the fun part," she said, "to create the equation of what she might have been when she was younger."

If the movie melds seamlessly with Vedder's music, it's because Penn structured the script with gaps in the narrative that would be plugged by music. He initially considered a mix of songs from singer-songwriters.

"More and more, through what Emile was doing on set, I started to think of Eddie's voice connecting and that it would dance well with the sort of musical soul of the character he was bringing on. That happened also to be the voice I loved most in terms of American rock," Penn said.

"I asked, he said yes, and then he got in a room with his muse and all this incredible stuff came out." And Penn used it to take moviegoers into the wild.