Hey,
Mac's Internship program is very convenient and well designed for students to get the most out of it. It is competitive to a degree, as you are competing for available openings at workplaces, but as long as you aren't overly picky, you will be able to get something you want.
You don't need a 12.0 GPA in order to get positions, but at the same time you're going to want your grades to be as high as they can, as it obviously reflects to the employer about your attitude at school. Having volunteer/prior work experience is also a plus.
Don't worry about competing with other schools however, as McMaster has a good relationship with many employers who I believe specifically recruit a certain amount of students strictly from Mac because of this internship program.
In your 3rd year, you have to take a non-credit course to prepare you for your internship, and it really guides you in teaching you exactly what you need to know, such as resume building, acceptable behavior in the workplace, etc.
Hopefully that answers all your questions!
