I guess no answers is an answer in and of itself :-)
I haven't actually worked with ZK (as in haven't deployed an actual product), but I've played with it a bit out of curiosity. Basic CRUD stuff works just fine with Hibernate, ZK has a chapter in documentation which shows how Hibernate should be set up. It's an extension of their basic tutorial. ZK used to have issues with Hibernate session management but that has been resolved in the later versions (using custom ZK listeners).
Hopefully that'll be enough to get you started. Again, I haven't done a real project with ZK so it's quite possible you'll hit on some issues once you get deeper into it - be sure to do some piloting if you're considering this for production.