This was my second time interviewing with McMaster. The first time was just out of college and they were not interested in me. At that time I was applying for a programming position. This time, with a few years of experience, I was being interviewed for a position in IT Audit. The initial interview was over the phone with their recruiter. Very basic questions to get a feel for the type of person I am and to see if I fit into their culture. I was just very honest about how I view work and how I view audit specifically, talked about my experiences in audit, times where I'd had challenges, etc. I was in a position where I already had a job, so I made it clear that this was as much about the position being right for me as it was me being right for the position.
The next interview was with their new director of audit. We had lunch and talked about my experience, my current job, techniques used on the job, etc. Was fairly laid back. Basically this was an interview with the person that would be my direct manager so he could get a feel of if he'd be able to work with me and if I had the proper skill set. Being personable is key here. Remember it's not just about what you can do, but about how well people can work with you. And people like to work with people that they enjoy being around.
After all of that I was invited to go out there and fill out paper work after meeting with a couple of C-level people; however I declined. I hope some of this is helpful!