nusa, were you able to figure out how to manually rollback transactions when using EJB3 + Seam managed transactions? I'm not sure I see a solution within the thread.
From my understanding, is if you use EJB3 + Seam managed transaction, then you can commit/rollback where you want, because it allows you to have a fine-grained control. But if you use Hibernate + SeamExtendedManagexxx, then you don't have that possibility, because it's a coarse-grained.
Maybe I'm wrong ...
My advice is if you need recovery, you should not use Seam-managed transactions. Use EJB3 container managed transactions, demarcated at component boundaries.