I applied through university. The process took 1 week. I interviewed at Harvard University (Cambridge, MA) in Feb 2015
Interview
One-on-one. Interviewer asked about my reaction as a proctor would be in different hypothetical scenarios. Very nice, got back to me later. Advice - read that sheet they hand out about summer school values.
Interview questions [1]
Question 1
Q: What would you do if there was a party in a your floor, other students can't study, so you knock and ask them to quiet down and they don't.