This is what we are adding to our JBoss command line while development:
-Xdebug -Xrunjdwp:transport=dt_socket,address=8787,server=y,suspend=n
Then we launch the eclipse remote debugging and connection to this port.
Update:
To run from jar (standalone) do the following
java -Xdebug -Xrunjdwp:transport=dt_socket,address=8585,server=y,suspend=n -jar start.jar