Ooo! This should be interesting. My scripting knowledge in Ruby is tiny, Java being my 'native' language. I've actually been working on a Java version for a bit. However, In a way, you can model the new battle system off the Essentials one.
a) Moves are largely the same
b) The only major change you make is with the actual battle scene. I'm not on Windows, so I can't have a look at the moment, however, you know that minigame with all the jumping around and stuff? Combine that, with the essentials battle system, do a bit of tweaking, and you *should* be largely done... I think