ET exclusively went behind the scenes of Ashley Greene's photo shoot for Teen Prom magazine, where the actress (a.k.a. vamp Alice Cullen) dished about her rigorous fight and stunt training for 'The Twilight Saga: Eclipse.'

"I was excited about the photo shoot. I wasn't too nervous, I've been in a prom dress before," said 22-year-old Ashley, looking glamorous in a strapless, floor-length purple gown.

"I'm trying to convince them to let me take the dress so I can go out in it," she giggled, "but I don't think it's going to happen."

Ashley, whose Teen Prom issue hits newsstands Dec. 22, also showed off a bruise on her arm (rendered practically invisible with makeup) that she sustained while training for the eagerly awaited third 'Twilight' film, 'Eclipse.'

"Until I had to shoot in prom dresses, I didn't get any bruises. I was doing really well," she smiled. "It's horrible, but it's been really fun. [Our moves] will look really, really good by the time we finally get to the fight sequence because in 'Eclipse' ... we have to fight this new-born vampire army."

She adds that her training involves "a lot of learning to run and jump off walls and land on people's shoulders, and flips and throwing your body just ways that you would never, under any circumstance, normally do."

'The Twilight Saga: Eclipse' arrives on the big screen June 30, 2010. Meanwhile, 'The Twilight Saga: New Moon' is in theaters now.

Ashley's Teen Prom cover dress will be donated to DonateMyDress.org, which collects gently-worn prom dresses and donates them to girls in need.