The reels kept coming in every few months to the Disney Channel offices in Burbank. A gawky pre-teen girl with a charming Tennessee drawl was determined to land the role of her dreams in a show that the kidvid cabler was developing about an everyday tween kid who happens to lead a double life as a rock star.

The great “Hannah Montana” hunt became the Disney Channel’s version of the search for Scarlett O’Hara, dragging on for more than a year. The first time Disney Channel entertainment prexy Gary Marsh and “Hannah” co-creator/executive producer Michael Poryes saw 11-year-old Miley Cyrus on tape, they thought she was adorable and well-spoken, but a little too young and unpolished to fit the “Hannah” bill.

But Miley’s persistence paid off. Just as producers were prepared to go to pilot with a more experienced moppet, another Miley reel arrived, this time, with another year of acting lessons under her rhinestone belt. They had their Hannah.

“We made a bet on Miley that she had that star quality, the charisma and the ‘it’ factor to create this role,” Marsh says. “For us, every casting session, every development project starts with the notion that we have to create our own stars. We don’t have the same established pool of talent” to select from as adult shows do.

Cyrus’ story of how she got the gig that turned her into a kidvid star is a good example of the unconventional talent scouting techniques used in the exploding world of tween- and teen-centric entertainment. Youth-oriented film, TV, music and DVD fare is a vibrant and fast-growing marketplace but one that remains dominated by the two powerhouse cablers that invented the contempo incarnation of the genre, Nickelodeon and Disney Channel.

For execs at both outfits, the search for fresh faces and potential breakout personalities is a 24/7, year-round pursuit that is a crucial element in their quest to remain hip and cool in the eyes of the most fickle of demographics.

“We meet with kids all the time, and we’re always looking for relatabilty,” says Paula Kaplan, executive VP of talent and West Coast general manager of Nickelodeon.

“What we’re always trying to (showcase) on Nick is people who are regular kids — not the beauty-pageant-winner kind of talent. And we like diversity. You’ll never see all blond girls on Nick, or all skinny girls. We live to mix it up so that the shows on air reflect the real world of a kid.”

But it takes more than schoolyard charm to make it in the high-stakes world of kidvid these days, especially if a moppet has designs on transitioning to grown-up roles later on. Talent reps who specialize in youth thesps say there’s never been more demand for triple-threat kids — witness the Disney Channel’s phenomenal worldwide success with its “High School Musical” tuner franchise. Given that kids now have ample platforms to become superstars in the tween universe, it’s more important than ever that youthful performers are wise to the ways of the industry and have a strong support network behind them.

The Nick teen fix

Nickelodeon is famous for its farm-team system of developing new shows around actors who are introduced to the Nick aud by supporting or guest-starring roles in other shows. It started more than a decade ago with the sketch comedy “All That,” when execs and producers couldn’t help but notice the chemistry between two of the troupers, Kenan Thompson and Kel Mitchell, who were given their own show, “Kenan and Kel.” Amanda Bynes, Nick Cannon and Jamie Lynn Spears also served stints on “All That” on their way to starring in their own Nick series. Bynes’ “The Amanda Show” featured Drake Bell and Josh Peck in supporting roles before they graduated to “Drake and Josh.” Miranda Cosgrove, star of Nick’s latest buzz-bin series “iCarly,” was a regular on “Drake and Josh.”

“I haven’t been out of production since 1994,” says writer-producer Dan Schneider, himself a one-time child actor who is now Nickelodeon’s most prolific supplier of programs, including “Amanda,” Spears’ “Zoey 101,” “Drake and Josh” and “iCarly.”

“All of my shows have been farmed from a previous show. We take casting even minor roles on all of our shows incredibly seriously because that’s how you keep it going,” Schneider says. “You remember people who impress you (in auditions). Even if they’re not right for the role we’re casting, I file them in the back of my head and when I’m casting something else they are right for I can just say ‘Aha! Go get that girl.'”

And once the show is ready to break, the kid star becomes the centerpiece of a multimedia marketing blitz that is usually focused more on launching its tyro entertainer as a new brand affiliated with a favorite channel than on strictly pumping the program. That’s one reason so many of the latest hot properties — including Disney Channel’s “Hannah” and “High School Musical” franchise or Nickelodeon’s “The Naked Brothers Band” — emphasize music, which makes for a natural ancillary marketing hook through recordings and live performances.

“The audience wants to have different access points for their (favorite) stars, and they want as much access as they can get,” Kaplan says.

Having a rich Web presence is vital, of course, but it all still comes down to the TV property to drive everything else. There won’t be much in the way of soundtrack sales, albums, books, merchandising or feature-film adaptations without a successful TV program to stoke demand and lend legitimacy to a newcomer.

“We have a lot of people come to us who now want the whole Disney package,” says Marsh, citing the company’s strength at cross-pollinating properties among its feature, publishing, Internet, music and theatrical productions. “We have to tell people, ‘One step at a time. Let us help develop your talents.’ Because it has to start out (on Disney Channel) to drive appeal. Once you’ve got that baseline level of awareness, then we can talk about what the extensions are, and with the right talent, the sky’s the limit.”

Instant messaging

The fast expansion of the tween/ teen market during the past dozen years has also had the effect of rewriting the rules of what it takes to become a kidvid star.

Forget the Shirley Temple model. For programs aimed at kids in the 6-15 range, execs and producers say, an actor must come off as extremely relatable to the aud in a kid-next-door way, yet their on-air personality has to be compelling enough to get a firm grip on a demo with short attention spans. Actors on Nickelodeon and Disney Channel live-action shows can’t be too over-the-top, but they can’t be too low-key either.

“A lot of kids are groomed through commercials, where the acting is bigger for the salesmanship factor. It can be a challenge to take them down a notch,” Marsh says. “But it’s easier to take someone down a notch than to raise them up a notch in terms of energy. If they’re too low-key, you don’t know if that’s a choice or a limitation.”

“A lot of it falls down to that first 10 seconds in the room and how they behave,” says Bonnie Liedtke, an agent with WMA who has specialized in repping kid actors for more than 20 years. Among her finds over the years have been Leonardo DiCaprio, Hilary Swank and “High School Musical’s” Zac Efron and Corbin Bleu.

In her first 10 years or so in the kidvid sector, the onus was on Liedtke to proactively scout for new faces. Now she doesn’t have enough hours in the day to see all the genuinely talented interested in booking an audition. The fact that there are so many more employment options for younger actors these days has made many more kids focused on breaking into showbiz, Liedtke says.

Popularity contest

Like most talent scouting processes, hopefuls generally come in the door at Disney Channel and Nick through agents, managers, casting directors and recommendations from others in the industry, particularly young actors themselves. Disney Channel execs periodically try to hold discreet open calls in various cities. They work through local talent reps and acting schools, and occasionally place a local ad that doesn’t identify it as a Disney Channel-hosted audition.

Two years ago they made the rounds, and out of 5,000 kids who cycled through their stops in a handful of cities, a girl from Texas stood out in Marsh’s mind. The young actress, Selena Gomez, was cast in the pilot for the spinoff of “Lizzie McGuire,” which didn’t go, and last year they gave her two more pilots, one of which became the recently launched series “The Wizards of Waverly Place.”

“That’s a question of betting on talent,” Marsh says. “Once you find the person, you’ve got to make a commitment to give them work to get their shot.”