How do you make a Leonard Cohen documentary without money, time - or, at first, the man himself? Lian Lunson tells Tony Clayton-Lea how she managed it

Edging its way into end-of-year top-10 lists for best documentary, Leonard Cohen: I'm Your Man is as moving and celebratory a tribute as you'll ever see to someone who is still alive and kicking. Featuring parallel threads of the travelling Came So Far For Beauty concert (from Sydney in early 2005) and grainy shots of the Canadian singer-songwriter and poet reflecting on aspects of his life, it is the sort of work that is as much life-affirming as it is a valediction.

It was not made as such, says director and producer Lian Lunson in the library of Dublin's Irish Film Institute. She agrees it might be trawled for suitable quotes at the point of Cohen's passing in years to come (though Cohen, she says, is still remarkably healthy for a man in his 70s). But she made the film for a different reason: "I wanted very much for people to pay tribute to him when he's around."

From Melbourne, Lunson is a former actor who moved to Los Angeles in the mid-1980s, initially to be in movies but gradually realising that she'd prefer to make them. Eventually, she formed her own production company and started working on her own projects; these include many music videos and occasional documentaries (including one on Willie Nelson).

It isn't easy to get Hollywood studios to finance documentaries, says Lunson. And when the subject matter is a man in his 70s with limited commercial appeal, it's even more of a struggle.

"The fans that love Leonard Cohen are legion," says Lunson, "but in Hollywood you have to find the right person. All of the names in the concert are fantastic, but most aren't major commercial names, so when Hal Willner [producer of the live concert event] told me that he was putting on a performance at the Sydney Opera House, I had a very small window of time to think about whether to put up my own money for the movie or whether other people would come on board."

Enter stage right an old friend of Lunson's - Mel Gibson (with whom she has worked on The Passion of the Christ). Although Gibson is a fan of Cohen's, she says, he wasn't interested in financing the film or, indeed, being involved in any way other than genuinely wanting to help. "So he took me to a meeting at [ film studio] Lionsgate, told them he supported my work and that it would be a great project for them. And they said okay."

Without Gibson, Lunson points out, she wouldn't have been able to go ahead and work on the film. "If I'd had a year to slog it out and pitch it, then perhaps it would have worked out, but I simply didn't have enough time."

With the green light from Lionsgate (predicated in part on Lunson's false claim that she had Cohen himself on board - "I was flying by the seat of my pants!"), she thrust herself into what she says turned out to be an organic experience.

Initial contact with the subject from late 2004 wasn't easy, she says - Cohen wasn't at all interested in anyone making a film about him. Letters were sent but not replied to. Gradually, a friendly detente was achieved through a six-hour conversation wherein Cohen gently grilled Lunson about what kind of a person she was and what precisely it was she wanted to do with her film.

"I walked away from that meeting with him thinking that if he is not going to be a part of this, then that was okay, that it was his decision." Thankfully, it didn't turn out that way; Cohen agreed to be filmed for up to five hours talking about whatever came to mind, prompted by Lunson's subtle questioning. She had editorial priorities, however, and so only a small section of what Cohen talked about made it into the film (extra interview footage will be included on the DVD).

"My first priority was to make sure that everyone in the concert was not left out of the movie. Then with Leonard, I felt what was more interesting to me about him was the essence of who he was; he really has something else going on inside him and that was what I wanted to capture in the movie, what I wanted people to take away from the film. Certainly, I felt that was more relevant than his personal, private life."

What perceptions of Cohen did Lunson have prior to meeting him?

"A handsome, insightful, intelligent, deeply religious man. He's quite anti-establishment, always has been, always appealed to the outsiders in a sense, while also being cool and liked by your auntie." Lunson has maintained a friendship with Cohen outside the professional confines of her film.

"They just don't make people like him any more. I'm drawn to spiritual wanderers - people searching for something. You spend so much time with a movie, and I couldn't do that if I didn't really admire the person or feel that the experience was going to enrich me spiritually or better me as a person."

Did she get a good sense of Cohen as a person? While admitting that she has barely scratched the surface of his wealth of experience, Lunson acknowledges that Cohen has "tapped into another worldliness - he has a foot in that door. Some people think they have, but he genuinely does. And that drives him; he doesn't conform to any sort of norm. He does what he believes is right. He's very kind, very nurturing, selfless, humble. There would be no reason whatsoever to question his belief systems because you know he's coming from a place of truth."

Lunson hopes the film will strike out the notion that his music is depressing. "He said to me that the people who don't understand his music think it's depressing. And the music isn't depressing at all when you really think about it - he'll certainly take you out to that dark place, but then he'll say to you, 'you know, ultimately it isn't that bad, you'll be alright.' "

Leonard Cohen: I'm Your Man opens nationwide on Oct 20. The soundtrack is available on Verve/Universal