I originally approached them at an on-campus career fair and was immediately granted an interview the next day after reviewing my resume. The interview was very casual and the question were either behavioral or related to my previous experience.
After some time, I was invited to their offices in Fairfax, VA for an on-site interview. I decided to go with the morning shift. There were several other college-aged students who were invited as well. The HR representatives took us on a quick tour of the offices and then reviewed the benefits and perks of CGI. We were then assigned to two 30 minute one-on-one interviews with consultants in the company. Most of the questions were behavioral. Some of the questions asked were very simple technical questions, such as "What is polymorphism?" and "How do you split a certain data structure?" After the two interviews, we were provided lunch and a panel of new hires who could answer any questions we had about the company. The panel of new hires did not factor into the company's decision to extend an offer or not.
It seems like the process depends on who you get to interview you. I originally thought one of the consultants didn't like me, but then I received a call saying that they would like to extend me an offer. There is no negotiation for entry level new hires. They will listen to your requests, but politely decline. You can only negotiate more time on your decision.