Apparently Kristen already plays the guitar, and has been brushing up on her vocal skills; the two were at the sound studio all day on Monday.
Kristen said, "It's one of the most immense responsibilities to play a real person. Her story's important. It's an incredibly triumphant feminist story really.
'She's the first woman to ever start her own record label. So many people know her as just being like one of the coolest people to ever live. That in itself is one of the most intimidating things that I've ever had to confront but she's so cool too.'
Joan is equally enthusiastic about Kristen: 'When her hair is cut and with the right make-up, Kristen should make a really good me.