<p>I want to move a legacy Java web application (J2EE) to a scripting language - any scripting language - in order to improve programming efficiency.</p>

<p>What is the easiest way to do this? Are there any automated tools that can convert the bulk of the business logic?</p>

Using an automated tool to "port" the web application will almost certainly guarantee that future programming efficiency will be minimised -- not improved.
A good scripting language can help programming efficiency when used by good programmers who understand good coding practices in that language.  Automated tools are usually not designed to output code that is elegent or well-written, only code that works.
You'll only get an improvement in programming efficiency after you've put in the effort to re-implement the web app -- which, due to the time required for the reimplementation, may or may not result in an improvement overall.