FlaZoomie has some good points. I have never taken a PMEL just a CMEL, so this would be for a commercial checkride, but this is what I would know if I were you.

I would be able to draw the fuel system. Know the electrical system very well, you don't have to be able to draw it, but close. Know what the pressures are for the retractable landing gear systems, and how it works very well. Be able to draw the prop governer system and be able to explain it in detail. Be able to tell him everything that affects Vmc and why, and what it does to performance. Be able to tell him everything that makes the crit engine critical and why.

If you can do all the above, you will have no problems at all. Remember, when you go to interview with an airline, they will ask you lots of questions about the most complex airplane that you have in your logbook, and it will probably be this plane, so you want to know it in and out anyways.