The short answer is: there is nothing yet to replace the old Embeddable EJB3 in a way that's usable for current scenarios.
Embeddable EJB3 Alpha 9 is an AS 5 Alpha preview (thus has Micro Container in it). There already where some incompability issues with AS 4 and when AS 5 started moving forward it was impossible to maintain an AS 4 compatible E-EJB3. So from your use case scenario it became unusable.
You can read more on this in the sticky: http://www.jboss.com/index.html?module=bb&op=viewtopic&t=103397
Right now we're working on EJB3 Standalone, which targets unit testing. But it'll only be compatible with AS 5, so even an Alpha release there will not be usable.
In AS 4 we use AS itself for tests, in AS 5 we got AS Micro which we augment with enough services to handle most EJB deployments. This will be the basis for EJB3 Standalone.
Thanks for the answer.
For me it is acceptable to unit tests some EJB 3 with Jboss microcontainer even if I deploy in JBoss AS 4.2.3. For unit tests I just use basic EJB3 features.
I also have integration tests in JBoss AS.
I have tried embedded JBoss beta 3 with JDK 1.6 using the magic jvm arguments (http://www.jboss.com/index.html?module=bb&op=viewtopic&t=132549)
That works fine ...