Useful tip I came across for remote debugging java webstart application.
Run the following two lines from the command line (or from your bat file).
set JAVAWS_VM_ARGS="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=4145"
javaws http://URL/JNLP_DESCRIPTOR.jnlp
javaws http://URL/JNLP_DESCRIPTOR.jnlp
cool tip quite helpful, here is another useful link related to 10 tips to debug java program in eclipse