I applied thru school's internship database. The whole process took about a month, including a screening phone interview and if you are selected, they have another interview with 2 or 3 other engineers. The interview was relatively easy. For interns, they mainly asked behavioral questions.

I spoke to them at the co-op fair at my university. Shortly after I received a phone call asking me to come back and do an interview while they were still on campus. That interview went well and they asked me to go on-site for a second interview which last ~8 hours and consisted of many individual interview sessions with various employees and a short tour of the site.