"Spirit" combines traditional and 3-D animation in a story about a wild stallion in the Old West.
Adams and Zimmer have already accompanied clips of the movie with live performances twice -- once at the movie industry's annual ShoWest convention in Las Vegas, and then at a DreamWorks party in Los Angeles.
Those limited performances served as something of a shakedown cruise for Zimmer and Adams, giving them an opportunity to get a feel for the process of live accompaniment before presenting the entire score at Cannes for an audience largely made up of influential filmmakers and writers.
Zimmer acknowledged in a recent interview that he was slightly anxious about the gig.
"If I let myself I would be completely terrified about this whole prospect," he said. "On the other hand how boring would it be if there wasn't an adventure at the end of this?"
Zimmer has composed the scores for some of the biggest hits in Hollywood over the past 15 years, including three of the highest-grossing movies of 2001 -- "Black Hawk Down," "Hannibal," and "Pearl Harbor." He had a pretty good year in 2000 as well, with "Mission: Impossible II", "Gladiator" and "The Road to El Dorado."
He won the Oscar in 1994 for "The Lion King."
The main characters in "Spirit," are horses. Apart from a voice-over, done by Matt Damon, they have no dialogue. As a result, Zimmer said, the music carries a heavier-than-usual portion of the storytelling burden.
"Bryan and I are, I would think, the voice of the movie," he said. "The narrative of the movie is entirely emotional because that's the only thing you can do with music."
Zimmer said it was the most difficult challenge he has ever taken on.
"Because if (the audience) didn't get it," he said, "guess whose fault that was."
The 44-year-old native of Frankfort, Germany is confident that his music on "Spirit" gets the job done.
"English is definitely not my first language," he said. "I do feel I'm far more eloquent in music. I think people do get the sense that something heroic is occurring in this movie."
Zimmer has employed a vast array of musical ideas in films such as "As Good as It Gets" (1997), "Thelma & Louise" (1991), "Driving Miss Daisy" (1989) and "Rain Man" (1988).
His score for "Spirit" seems to contain traces of classic movie Western music and the work of Aaron Copland. Zimmer said he consciously tried to avoid referring to Copland, but almost irresistibly ended up going back to Irish music and other sources of Copland's inspiration.
There is even a tango, accompanying a scene in which the young stallion gets frisky with a filly. Zimmer conceded that the piece was anachronistic, but it served its purpose.
"I needed a symbol that said sexual flirtation," he said Zimmer. "There's no point making an animated film unless you can step outside reality."
The composer said Jeffrey Katzenberg, who oversaw the project for DreamWorks, encouraged that kind of out-of-the-box thinking.
"They let me do my thing and support me in my crazy ideas," he said. "There must have been a couple of fights Jeffrey and I had. I did the score three times -- at least had a stab at three times. I couldn't figure out how to make it work."
After composing close to a dozen scores in the past three years, Zimmer said he is ready to take a break. However, he expects that when he goes back to work, it will take him a while to get back in a composing groove.
"If you just write every day you stay in training," he said. "New ideas just keep happening all then time. I'm not saying it's easy. I'm not Elton John, who can sit down and 20 minutes later has a hit song."
"Spirit" opens in U.S. theaters on May 24.