Step into William Ivey Long’s “Grease Live” lair on the Warner Bros. lot in L.A., and you’ll feel like you were transported back to Broadway.

The costume designer has decorated his walls with inspiration: stills from the original movie, multi-colored fabric swatches and photos of “bad boys of all time.” Next to Marlon Brando hangs a photo of James Dean — because “our Danny is blonde,” says Long, referring to star Aaron Tveit.

With 30 costumers in total, many of whom come with a background in New York theater, the hustle and bustle of the wardrobe department is a sharp contrast to the relatively calm soundstage. Fast-moving staffers weave in and out of rolling racks and alteration rooms with razor-sharp focus — so much so that the visitors on set can’t help but note that these Broadway types don’t mess around.

“This is a Broadway musical and filmed like a movie but on television,” says Long, who’s won six Tony awards, and is famed for his work on over sixty Broadway productions including “The Producers” and “Hairspray.”

Yet for such a large production — 407 costumes just for the principal cast and another 226 for extras — Long, who’s tasked with the design of all “Grease Live” looks, is working out of a tiny, closet-like space. But despite the size of his workspace, the imagination and creativity pouring out of the room is immeasurable. And with just days before showtime, Long — a seasoned stage veteran — is taking care of the details himself.

Dressed impeccably in a tailored suit with a dapper tie and thick-rimmed glasses, he’s hand-painting scorpions through a stencil onto leather jackets. Why not have the designs screen-printed? The T-Birds would have hand-painted themselves, he explains.

Still, he admits Fox’s live television event, set to air January 31, is a lot of work. “Oh my goodness, there are hundreds,” he says of all the costumes he’s designing. “We just got our extras — 52 of them — three complete looks. And the football team, that’s 200 looks right there. It has to be an entire high school!”

At the same recent rehearsal where Long was creating painted scorpions, Julianne Hough, who plays Sandy, was raving about working with costume designer, who’s a favorite among all cast and crews with whom he works.

“I don’t even actually know exactly what I’m wearing — we just fit so many things!” Hough told Variety in an interview earlier this month. Her favorite looks, she said, are Sandy’s cheerleader outfit and a vintage swimsuit, for which she endearingly exclaimed, “The zipper is so old!”

As for Long, one of his favorite looks is the glamazon outfit worn by Keke Palmer’s Marty, after she transforms from her pajamas in the Pink Ladies’ slumber party scene. Long relates the diverse selection of clothing to the casting. “We’re looking at the ’50s in a today eye,” he says, “just as our cast is multi-racial, which it would have not been in 1958.”

With a collage made for every outfit and hand-drawn sketches, Long — who has also been tapped as costume designer on Fox’s upcoming “Rocky Horror Picture Show” special — has done everything from sewn curlers onto hairpieces, placed hundreds of sequins on fabric and distressed yards of denim. “I have to finish aging all the overalls in ‘Greased Lighting,'” he says, as he removes a scorpion stencil from another garment.

Aside from overalls, the “Greased Lighting” boys’ pants are also getting a makeover. Pointing to a photo of Brando wearing high-waisted, loose dungarees, Long explains the musical’s looks will stylistically be old fashioned, but with a modern fit, so he designed the men’s pants to resonate with audiences who are accustomed to the “tighter fit of today.”

Hough, for one, appreciates Long’s intricate eye for detail. “Putting on those clothes, you just automatically stand a little bit more upright, your shoulders kind of curl back a little bit more,” she said with a smile. “That’s one era that I really wish I was born in. I love the ‘50s.”