It's rare that one sees a movie that re-imagines a stodgy genre, but next month's "Take the Lead" is a long way from your standard inspirational-teacher flick. When Antonio Banderas' suave substitute strolls into a New York public school and mixes his love of ballroom dancing with the troubled students' hip-hop, the results might inspire some audience members to take a twirl in the aisles.

The story behind the film's complicated soundtrack, meanwhile, could make their heads spin.

"I was a music lawyer for a while, and I've been the music supervisor on about 50 movies," explained Bonnie Greenberg. "But this is the most complicated thing I've ever done."

Music video veteran and first-time film director Liz Friedlander, along with Greenberg, set out to create a complicated pastiche of old and new, crafting a soundtrack that could rival mixes such as Danger Mouse's The Grey Album or DJ Z-Trip's Uneasy Listening. Try to imagine the complications of mashing together multiple songs by classical artists and cutting-edge rappers, then navigating the treacherous legal waters of royalty payments, and then attempting to fit it all into a movie filmed with temporary music and dependent on the perfect notes hitting at the right moments.

"It's very difficult to pull off and, frankly, [the legal part] is tougher than the creative part," said Greenberg, who built her career on music-driven flicks like "Hairspray" and "My Best Friend's Wedding." "Our mash-ups would change 15 different times. Every time something changed, it altered the overall percentage of who contributed what in the song."

As Greenberg mixed and matched the music in accordance with the legal wrangling behind the scenes, Friedlander shot her movie with music that would later be replaced.

"We had to do it progressively each time, and when it looked like someone might be difficult [and we couldn't reach an agreement], we took them out and put someone else in."

One of Greenberg's greatest regrets came via an early-'90s hit that they simply couldn't wait around for any longer.

"We really wanted to use Tone Loc's 'Funky Cold Medina,' " she remembered. "We had to take it out because at the end of the day we couldn't work a deal where we gave Tone Loc a certain percentage, and the Gershwins and Jae Millz and Mashonda and Akon and Erik B. and Rakim. There were, like, seven different people in the mash-up."

Everything had to add up to 100 percent, but artists and lawyers frequently clashed over the exact percentage of a song that featured their material.

"Remember when Linkin Park and Jay-Z won a Grammy for their mash-up and in their [Grammy] speech they thanked all the lawyers? I completely understand that now," Greenberg sighed.

"On top of that," she continued. "We had visuals that had to hit. We had to make transitional changes visually, we had to make them legally, and then our mash-up guy had to work together musically in that same key."

Nevertheless, Greenberg is thrilled with the final product, stuffed with genre-bending grooves that should give tango aficionados and hip-hop fans a newfound appreciation for their respective loves. She was eager, as well, to offer a rare preview of three of her favorite scenes from the film, along with what she was thinking as she put the music together.

The first scene is an adrenaline-pumping, rebellious moment with the outcast students temporarily breaking the monotony of detention by busting out their own moves.

"That scene we shot to a certain tempo because we wanted to maintain a certain energy. Freeway's manager saw it, and they had this brand new track that was already completed, so they called me and played it for me. It was this LL Cool J and Freeway track demo. I said, 'Oh my God, that song is perfect.'

"I took it back to L.A. with me and played it against the scene. It was completely the right vibe, and Liz loved it. Def Jam and all the people from Freeway's and LL's camps loved the movie so much that we figured out a way to make it work. Some of the samples were removed from the track, but it still turned out to be one of the costliest tracks in the film."

The second scene has Banderas introducing a classic by George and Ira Gershwin to his visibly pained students. Later in the film, the kids mash in their own beats to give the Gershwin tune a modern edge.

"The Gershwin family read and approved the script. We were involved with one of the lines of dialogue, where Antonio specifically pays homage to the Gershwins.

"For that scene, we wanted to find something quote-unquote 'square' that the kids wouldn't respond to," Greenberg laughed. "We decided to go with 'They Can't Take That Away From Me' because it's a classic song that people will recognize -- but we decided to go with a non-classic version of it. I went and listened to over 150 versions, looking for something sparse that could be merged. Part of a mash-up is that the keys have to musically collide, or else it sounds like big bowl of soup."

The third scene has one of Banderas' students using a brief song segment to explain that the Gershwin vision of romance is ancient history.

"It had to be a hip-hop song that right away made its point and right away was something vulgar. Our description when we sent this out to songwriters was, 'As vulgar as you can get, but still staying PG-13.' That's tricky. You have to make the point right away, not 20 seconds into it."

When the film opens on April 7, moviegoers can decide for themselves if the point has been made.

Check out everything we've got on "Take the Lead."

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