Any time you are applying for the DCP you have to apply through the Disney Careers website, no matter the school. It's just like a regular job or internship application. So that is a good place for your DS to start, here is the web link for the Disney Careers CP page, which is where the application will be when it goes up in the fall:
http://cp.disneycareers.com/en/default/
From there, if you are accepted, that is when you would start working with your school, if they have a department or program to specifically work with it or an academic advisor. If St. Clair has a program that works with the DCP, I would say just have your DS contact the chairperson for that to see the specifics for the school, as each school looks at the program differently. For example, my school just counts it as an internship, and treats it the same way as any other internship, but some schools do not accept it as credit or know what the program is, so some people have to "take a semester off" to do the program.
For timing, you apply the semester before you would participate in the program, usually about beginning to mid-semester. The two times for programs are Fall, which is the beginning of August to usually the first week in January, and Spring, which is end of January to mid-May. The program lasts the entire time period with a full schedule, so you can't take college courses at the same time unless they are online from your school, or the Disney offered classes, which is why most people use it as an internship or a semester off.
Hope that helped! If you have any other questions feel free to ask, or have your DS contact his school to see if they have any information about their specifics!
- Sam