It is very, very easy. You can see the sheet they use to grade you on PSIA's website, its all very simple and if you've been teaching for three years should be second nature. It's pretty hard to fail.
You'll do a movement analysis section that includes a video and following lesson plan, and you will also demonstrate your lesson plan in the second on-snow section. Both of these parts you will present as a group with a few other people in your cert. In your level two cert, you're on your own for this part.
I did a two day cert trip and the first day we basically ski'd with our certifiers, they were laid back, gave tips and if you applied them to your skiing, you passed. We only skied and had them grade our skiing for a few sections of a few runs and it was very easy.
The bottom line is that the level one cert is meant to be a learning experience that kind of gets you ready for the setting of the level two, which will be far more intense in terms of movement analysis, teaching, and especially skiing. Moguls are a bitch for level two, and where most people fail.
"I drank three bottles of champagne and hung out with a stray dog all night under a bridge. It was sweet."