I just published my first tutorial/article on my new blog for unpacking/extracting the original Jar archive/executable from a Java application that is wrapped in Launch4j. I also included the steps to recover command line arguments that launch4j passes to the java runtime. I hope that you enjoy and learn a few things.
Link:
http://reverseengineeringtips.blogspot.com/2014/12/unpacking-launch4j-35-extracting-jar.html