"Literally, I shot for like an hour and a half, and I was done," Cyrus told Ryan Seacrest on his KIIS-FM radio show on Friday. "it was a total dream come true."
Cyrus, who plays herself in the movie, causes problems for Kim Cattrall's character, Samantha Jones, by wearing the same dress as the older woman to a movie premiere. "Working with Kim was really cool," Cyrus says. "And Sarah Jessica Parker was the nicest person in the world."
The pop star, who turns 17 on Nov. 23, also talked about her birthday plans, which reveal her to be something of a Dolly Parton fanatic.
"I want to rent out a cool place and play all Dolly Parton music and have everyone dress up as their favorite Dolly moment," says Cyrus, who was born in Nashville. "I am really excited about getting all my crew members to dress up as Dolly. That's probably going to be the funniest thing ever."
Cyrus is currently on tour with her older brother Trace, whose pop band Metro Station is opening for her.
"We're having so much fun," Miley says. "This is the most I've seen my brother in like four years, so it's kind of crazy. It's really cool to have our family all together."