The students stared at the overhead screen and read the words in unison:

Labbaik. Allah humma labbaik.

The Southern California Muslims repeated those words -- "Here I am, Lord. I am here to serve you" -- as they donned pilgrims' robes last week in the Saudi Arabian city of Medina, a key step on their pilgrimage to Mecca.

On the night they watched the overhead projector, the pilgrims-to-be had assembled in a more prosaic spot, a mosque tucked in a nondescript Costa Mesa office park in the shadow of John Wayne Airport. They were gathered with their teacher, Imam Moustafa Al-Qazwini, to learn the intricate and ancient rituals surrounding the hajj, the pilgrimage that is considered the spiritual pinnacle of a devout Muslim's life.

"You are telling the Lord: I have traveled all this distance, left my home and my business," Qazwini said. "Here I am, Lord. I'm available for you. I am your servant."

Equal parts spiritual odyssey and physical endurance test, the hajj often demands years of planning, hoping and saving -- all culminating in an intense, sometimes dangerously chaotic five-day whirlwind.

This year, the hajj begins today. To help prepare about 25 of his students, Qazwini, 46, head of the Islamic Educational Center of Orange County, had organized a series of "hajj lessons" starting in late November. In them, he guided his charges through discussions that ranged from the spiritual (ask forgiveness of people you have offended) to the practical (the best places in Anaheim to buy hajj robes).

His tone ranged from high school teacher to stand-up comic. Pilgrims are prohibited from wearing cologne, perfume or beauty products, he taught, explaining: "You have to be as natural as God created you."

"But you do have to take showers, please!" he added, drawing a laugh from his students.

Another hajj stricture: No physical intimacy -- not even kissing -- is permitted during the several-day span when the pilgrims are in the state of holiness and purity known as ihram. But the no-sex rule would not apply to their entire three-week stay in Saudi Arabia, he added.

"So don't worry," he said, grinning.

For the pilgrims in Qazwini's group, the mix of the sacred and the practical filled the weeks leading up to their departure.

"You're spending all this time getting ready and running around and you almost don't have time to think about the spiritual experience," said Ellen Hajjali, who is making the pilgrimage with her husband, Raef.

"It won't hit us until we're actually there," said Raef Hajjali, 51, a construction manager.

"No. It'll hit me on the plane when I won't have any more lesson plans to do," said Ellen Hajjali, 46, a teacher at the New Horizon School in Pasadena.

At home in Altadena the week before their departure, the Hajjalis showed off their ihram clothes -- the simple white robes that all pilgrims wear -- and detailed their daunting pre-trip to-do list: Raef Hajjali had been advised by hajj veterans that, amid the crush of pilgrims, it's almost impossible to find your sandals after taking them off at the mosque door, so the couple were scrambling to buy multiple pairs.

Ellen Hajjali fretted about whether to take extra eyeglasses in case hers were crushed in the crowds. She also worried about what she called "the bathroom situation" on the desert plain of Muzdalifa, where an estimated 3 million pilgrims will hold a prayer vigil Tuesday and sleep on the ground under the stars.

Qazwini warned during his hajj lessons that the public bathroom lines in Muzdalifa are "longer than Disneyland's."

"It'll be like camping -- just with 3 million other people," Ellen Hajjali said, trying to put a brave face on the situation.