Try not to worry too much about what specific questions are asked and prepare to much for them, you may not get the same questions. I've just sat and passed my Psych/MMI to Enhanced for Northern which I'm sure will be similar to yours.
You'll do a SJE and select what you think of behaving a certain way in a number of situations, and the questions for your MMI will be selected from a list of possible questions they have on a list, to probe you about the type of person you reveal yourself to be in the SJE.
They're along the lines of application questions, "tell us about a time when...". Before you go in to MMI they'll give you a pre interview form to fill where you can make little notes about your answers, which you'll expand on in the MMI. Just stay calm and friendly, ask for a moment to compose yourself if you need it, hit all the right notes on your attitude to safety and protocols and I'm sure you'll be fine.
I should point out that this was my experience with Northern and other TOC's may vary, but I doubt it will be any different given that they're standardised.
Good luck.