IMPORTANT: This process has very likely changed since I was hired.
Submitted resume via email to the job. Heard back within a day or two to schedule a phone interview. Phone interview asked questions such as: Why did you choose Purdue? What are your interests? How would you convince someone who knew nothing about Purdue to come to this school?
Immediately after answering the interview questions, I was offered to come in for a face-to-face interview. At this interview, similar questions were asked. I had to spontaneously convince the interviewer why she should buy my watch. If I recall correctly, the same person did both interviews and hired me. She was also a student worker.
After being hired, there is about a week or two of paid training, and then you start for real on a "probationary" period for about another 2 weeks.