Unfortunately, JBoss no longer ships with a J2EE Dev Kit. And, even more unfortunately, Sun do not provide a standalone JDK for Mac OS X.
BEA WebLogic 9 ships with a modified version of the Sun 1.5 JDK but, alas, it's not available for OS X
To be honest, OS X is not the best choice for professional J2EE development - it's all much easier on Linux, Windows or Sun Solaris.