Years ago, a bright young kid could start out in the mailroom of a big Hollywood agency and learn the agenting game. Forget multiple degrees — a high school diploma wasn’t even a necessity.

William Morris eminence gris Norman Brokaw is a classic example. He started in the mailroom at the age of 15 and eventually made his way to the top of one the biggest agencies around.

That same path, traveled by many a legend, led to the training programs now in place at the top percenteries. But thanks to a glut of highly educated and driven contenders, a shrinking minority of today’s hopefuls make it from trainee to full-fledged agent.

“Deals are more complicated than they used to be,” observes one entertainment lawyer. “Many come with an assortment of built-in options, films are often locked up in franchises, and it takes skilled negotiators to pull it off.”

Rising to the dealmaking level takes more than just a degree. Those aspiring to be the next Jeff Berg or Jim Wiatt must come fully equipped with a healthy psychological fortitude (to put up with angst-producing demands and a daily dose of lying and scheming), an eagerness to please and, above all, the ability to keep firmly focused on the goal.

In talking to trainees and assistants from the five major agencies and several smaller ones, a recurring theme became clear. As a current assistant puts it, “Becoming an agent is a marathon, not a 100-yard dash.”

Just getting in the door means knowing the right people. Networking is an important skill from the very beginning. Most agencies want referrals, especially for the trainee programs.

Agency training programs have always been the best way to evolve into that particular creature known as the Hollywood agent. At larger agencies, like CAA or William Morris, only assistants who were formally trainees can be promoted to agents.

Unfortunately for those hoping to launch careers, training programs can lead to three to five years of frustration, embarrassment and general disillusionment before the goal becomes a reality.

David Kekst, VP of administration for WMA, estimates that 20-25% of WMA trainees do go on to become agents. Many of the others use the program as a stepping stone to other parts of the industry (some trainees will become personal assistants to agency clients), while most just burn out.

The trainee’s first stop is always the mailroom. Although a lucky few speed through, at a big agency like CAA or William Morris trainees can spend a year (or even longer) in the mailroom alone. In today’s agent game, a mailroom stint does not guarantee you will even see the ladder, let alone climb it.

William Morris is the granddaddy of the training programs. The program is both the oldest, at more than 60 years, and the largest, with 40-45 trainees in the Beverly Hills office. Other agencies tend to have only around two dozen trainees.

Kekst, who is in on the hiring of all trainees at WMA, says the agency looks for “a certain charisma” in candidates and to see if they are “aggressive, self starting and able to take initiative.”

Those are important traits for surviving the trainee world. Agency higher powers view training programs as a good opportunity to build mental fortitude in possible future agents.

As Kekst puts it, “One of the benefits is being able to discourage people who might not be committed or willing to pay their dues.” “You could tell who would make it and who wouldn’t,” remembers a current assistant. “There was one guy who was always having meltdowns in the mailroom. He never got promoted.”

The mailroom is a rite of passage no matter the age or educational background of a candidate.

Another trainee recalls seeing “32-year-olds come in with Master’s degrees after eight years of college and they have to push these carts around with mail in them. It’s sobering but it’s also funny. These people wanted to change what they were doing so bad that they came to Hollywood because they think it’s easy.”

Providing candidates with other kinds of training outside of the sorting and delivering of mail during this period is up to the agency.

That next step up from the mailroom is a position “on a desk” (i.e. becoming an assistant). If the phrase “on the desk of . . .” conjures up images of a poor young soul splayed out helplessly in front of an ultra-demanding, “experienced” tenpercenter you are not far off.

The relationship between agent and assistant is often tenuous at best — at least one challenge grasped by Michael Ovitz’s AMG. The company had a comprehensive mentoring and guest-speaker program to help underlings feel more connected to the veterans.

On the record, of course, agents aren’t all that bad. They have their moments but hey, everyone’s human.

Off the record, the stories can make the James Spader-Maggie Gyllenhaal relationship in “Secretary” look tame.

“The agents will yell at you every single day and then say one day ‘I love you, you’re so great, thank you so much’ and supposedly that makes up for it,” adds a former assistant.

No request is too big, or too small.

Picking up dry cleaning so your boss can have a clean tux for his son’s bar mitzvah; braving the 405 to hand-deliver award show tickets; explaining that a phone line is necessary for dial-up Internet access; making sure the right blend of coffee is always available and there’s not too much pepper on the tuna melt — all are part of assistants’ existence.

“When something needs to be done, it doesn’t matter if it has to be done on Mars, it’s your responsibility to figure out how to get it done,” says a seasoned vet with a wry smile. “You’re not allowed to mess up, it’s as simple as that.”

On top of coping with agents’ whims, assistants often have to help cater to clients.

“We had a client who was repped because her boyfriend was famous,” says a former assistant at a Big Five agency. “She skipped out on auditions all the time. I would have to call the casting director, make up some excuse for why she didn’t show up and beg for another audition. Other times she would call and say ‘I’m shopping at Barney’s and I’m really bored, let’s just chat.’ ”

Those skilled enough to deal with the mind games may encounter an even more formidable roadblock.

A former assistant who left a position at one agency for a training program at another explains, “The difficult trap you fall into is that you want to be a good enough assistant that your boss is willing to help you but you don’t want to be so good that you’re boss won’t let you go.”

That trap is more common than it should be, especially considering the vital roles assistants play in the success of their superiors (whether those superiors want to admit it or not).

Why do so many go through this numbing process that can eat away years of your life?

Well, the rewards are obvious: money, power, fame. It’s an irresistible lifestyle.

Sue Naegle, who runs UTA’s training program with Jay Sures and Adam Isaacs, maintains, “This is one of the only industries left without a glass ceiling. There is no limit to what you can achieve.”

Even if working your way up the ladder may be something akin to navigating a minefield, there’s always the acute awareness of numerous other young hopefuls nipping at your heels to keep you moving foreward.

In the words of one former CAA trainee, “You gotta be hungrier than the next guy, and the one after him. Lots of trainees burn out. They can’t see the light. It’s really about who can stick it out the longest.”

And what happened to that trainee?

He became a lawyer.

(Jill Feiwell and Lisa Hirsch contributed to this report.)