I think the minor is mostly self-selective. I think fewer than 20 people audition each semester. Everyone I know who auditioned got in, but I only knew a few other people who auditioned. I know my audition wasn't the best, but they accepted me anyways.
The School of Theatre offers dance classes every semester. MT minor students are required to take one dance class or movement or the musical theatre audition class, but I don't think there's a cap on how many you can take. THTR | USC Schedule of Classes
The dance classes offered are THTR 181-189. I think they may be adding a pointe class as well.
I haven't done the dance component yet, so I can't tell you how intense it is!
Here's the breakdown of required classes for the minor: USC Catalogue: The Schools: USC Thornton School of Music: Minors in Music