Red hot! A sneak peek at Raven-Symoné in her custom-made Tadashi Shoji dress. Photo: Marshall Heyman

When the actress, pop-star and all-around-phenomenon Raven-Symoné walks in the Heart Truth Red Dress Collection runway show this Thursday, she will be wearing a gown that was custom-fitted and dyed for her by the Los Angeles-based designer Tadashi Shoji. The former star of "The Cosby Show" and "That's So Raven" was at Tadashi's studio last week for her final fitting, which she shared exclusively with StyleList.

The actress arrived looking great - with a huge Louis Vuitton tote on her arm and wearing a glamorous Vivienne Tam day-dress. "It's from my mom's closet," she explained in a raspy voice that was caused by overzealous air conditioning in her new Sherman Oaks home. "I had it and then she took it for like four years, and now it's vintage, so I said, 'Ok give it back.'"

When Raven tried on the red dress that she'll be wearing on the runway, however, she was totally transformed. "I feel like Marilyn Monroe," she said, looking at herself in the mirror. (Though the designer himself wasn't there to witness the glamorousness - one of his assistants was helping with the fitting - we know he'd be proud.)

Part of the transformation came courtesy of an "apparatus" she has created for herself, an undergarment that's part corset, part Spanx. "Over the years of 'That's So Raven' and fluctuating and trying everything, I was like, I need to move this over here, move this here, put that there," she said.

The apparatus in question "makes the butt come out," according to the actress and recording star. "Normally Spanx makes the butt look flat, which is unacceptable for a black girl. No flat b. This molds and it lifts. Learn from Beyoncé all day long."

Eventually, when Raven starts a fashion line - something she is working on with a yet-to-be-named clothing company -she hopes to include this particular garment.

"When you do a line, you have to have something that sets it apart," she said. "I need to find that something so it's like, 'Did you hear what Raven has?'"

Regardless, "It will be affordable to all and cater to the girl who is very luscious."

Even though she looked fabulous, Raven explained that she has no anxiety about appearing in the upcoming fashion show. "The only time I was scared," she said, "was when I met Michael Jackson and when I met Janet Jackson. I almost fainted."

Come Thursday, those in attendance can watch her confidently strut down the runway like another famous catwalker. "I'm coming for Naomi," she said with a laugh.

Speaking of Naomi Campbell, have you heard what she's up to this Fashion Week?