I had an interview with the west coast accessions officer for a lateral transfer, so it may be a little different.
One thing he asked was "six adjectives to describe yourself" Another he asked was why should I be selected for the CEC (at the time, lat xfer slots were few, but have since opened up). You may or may not get that one.
Basically, he's going to try to judge your motivation for the program and verbal composure and things like that. Don't be afraid to tell him why you want to be in the CEC, and also, like any interview, bring your own questions you may have about the CEC.
If you haven't done so already, you can do a little homework at
www.cec.navy.mil
Good luck!