Sadly, saving files in this version in the .LVL format used by LaserTank 4.1 isn't possible without some sacrifices... I added a few new features that break backward compatibility, but make levels more interesting.
With all that said... I've also posted some test builds for you guys to play with.
http://lasertank.worldwizard.net/prelim/LaserTankMac.zip (Mac OS X version)
http://lasertank.worldwizard.net/prelim/LaserTankOthers.zip (Generic JAR for other platforms)
http://lasertank.worldwizard.net/prelim/LaserTankSource.zip (Source Code - Built with Eclipse 3.6 SR1)