I applied online to be an SNA at Western Psychiatric Institute and Clinic (WPIC). I got a call back, I would say, to weeks later (a few friends of mine applied using me as a reference and their call back times varied, but I would say give them a call after 3 weeks). I'm not sure how the process works for MT's. But as an SNA they actually ask you what your mental health interest is. You meet the recruiter, and then they tell you who you are meeting with. I interviewed on three floors. Your interview consists of a few different parts. One is a sit down with the NCM, or ANCM of the floor. They ask you typical questions, basically autobiographical questions, and the "why do you want to work here" types of questions. Then they give you a tour of the floor and tell you a bout the job. They also ask if you have any questions.
ADVICE:
My advice would be don't be nervous. The interview process for an SNA position at WPIC isn't tough at all. It's basically like "Does this person seem like they would be a good fit? Do they seem excited to work in the MH industry?" etc. Remember, you have to have your ACT 33/34, FBI, and PA child abuse clearances in order to work at WPIC (UPMC makes it easy to get all of these). When you come back from the interviews they will actually ask you what floor you like the best, tell them! They really want to know! I found out later that the NCM's typically quarrel over who gets who, so telling them is a plus. UPMC seems to like assertiveness, and people who are themselves. Remember this is WPIC, it's a mental health facility, so being personable is also a plus.
Don't be scared if there are other people. I got nervous and thought it was a group interview. It's not! When I went there were two other people interviewing for an SNA position. Not sure if they were interviewing on the same floors, but I know two out of the three of us got hired.
Lastly, BE YOURSELF! Since this is a student position, employers want to hear about school, make sure you focus on your major and how it applies to the job.
Good luck!