Indeed, this shouldn't be a problem.
You can even map Hibernate based component to database views.
As far as doing compound keys, it's easy. Here's a simple table with two fields acting as keys together:
That scenario can be mapped as simply as using the following class:
You can find the whole example here:
Hibernate and Compound Primary Keys -Cameron McKenzie
[ July 24, 2008: Message edited by: Cameron Wallace McKenzie ]