OK, just some notes. To decompile any java jar, use something like this:

javap -c -classpath ./semacoderead.jar org.semacode.imagerec.Ecc200Decoder 

I'm using mpowerplayer on OS X to do my J2ME compiling, which makes things pretty easy, except that I want to use the ProGuard obfuscator. Obviously! You NEED to obfuscate if you've got code like mine (for semacode) that needs to be protected from reverse engineering which is SUPER easy with java. It's available from fink.