Big surprise, I've been procrastinating again. The Polyglot environment that I had set up in Eclipse wasn't quite right, so I spent most of last weekend fixing that. I managed to get a test language change to work; boolj is Java except that the keyword for boolean has been changed to bool, and the booljc was able to build a Java program that just declares a bool.
The first step I'm going to take in implementing a DS Java is to make a language that has a set of global variables in its own space, with get and set operations. (In other words, there'll be a singleton HashMap<Object> with a funny name, and the get and set operations will translate into HashMap.get and HashMap.set.) Building this will do something similar to what I want to achieve in a quick and dirty way, and it should get me comfortable working with the Polyglot framework.