Hey Bart, I use JDeveloper as well. I love that combination! just go into the %JBOSS_HOME%/bin/run.bat and remove the REM from the line that reads
rem set JAVA_OPTS=-classic -Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,address=8787,server=y,suspend=y %JAVA_OPTS%
also change the suspend=n
then once inside JDeveloper just go into the projects properties and change the remote debug to "Attach to JPDA"
then Rock on. :)
gotta love EJB tools that don't cost anything eh?