A better way to state your question is, "can I put water-based acrylic paint over oil-based and/or oil-based over water-based acrylic?"
In the paint industry "enamel" has come to mean a paint that dries with a hard, durable surface. It is no longer a term solely the property of oil-based paint as there are water-based enamel paints available.
Personally, I use water-based craft paints for all my cresting. It's inexpensive, compatible with the clear coat I use, and it's available in far more colors than oil-based model paints like Testors.
Guy