On the set: ''Runaways'' -- The ''Twilight'' star and rock legend come together for the indie biopic

This summer, Joan Jett was given the opportunity to relive her teen years as executive producer of The Runaways, starring Twilight‘s Kristen Stewart as a young, red-leather-jumpsuit-clad version of…Joan Jett. The indie biopic (which has no release date yet) follows the rise and fall of Jett’s short-lived first band, the all-girl Runaways. The group made a name for itself, Jett remembers, ”scaring the s— out of people just by showing up.” So what was it like for the legend to sit around watching Stewart re-create her early life? ”It’s really hard to put exact words on it beyond saying it’s surreal,” Jett says. She and Stewart worked closely together on the actress’ portrayal. Jett gave Stewart tapes she had recorded at the age of 14 — tapes of her talking and singing that she’d made for her aunt. Stewart, 19, spent weeks listening to them in order to capture what the guitarist sounded like as a teenager — ”a combination of Maryland-East Coast-Philadelphia slang,” says Jett. Stewart was also able to consult with the rocker during filming in Los Angeles. ”I’m sure it was a strange pressure [on Stewart],” says Jett of her constant presence on set. ”She was kind of intimidated by it, but by the same token she wanted me there.” Among other things, Stewart asked Jett to read specific lines for her and to demonstrate certain guitar chords. ”I was there to be a resource for Kristen. She watched me a lot — the way I spoke, the way I talked, the way I moved in space, everything,” says Jett. ”But when it came down to the performing, the most advice I gave her was to trust her instincts. If something was really off, then we’d both know it. That occasion really never came.” </p