I've been playing around a lot with the creation of cellZones and faceZones and here is what I have to report !
Till now I have found 3 ways to do it. ( I am sure there are more)
1. To use setSet utility and cellZonesSet and faceZoneSet commands.
This works amazingly well and creates the zones. A small problem can arrise if you are trying to set zones for an internal flow case and at the center of your geometry you have level 0 cells....