Wow, doesn't seem like anyone is interested.
It'd be too much work for me to take on. I just picked the game up myself, played and beat it a few times (doing different things each time) and finally beating Hell and Ballos.
Now I'm messing around with Miza, trying to get a nice map played...
It's suggested that you make a 2nd copy of Cave Story on your computer and use it for editing purposes.
Once you've done that, enter the main folder and open the properties. Then click the "Read-Only" box so that it's UNCHECKED and then apply changes to that folder and all folders inside it...
Using Miza reminds me of the old Pokemon editor used back for R/B and G/S games. Able to edit sprites, move event triggers, edit event triggers, etc...
It's all made easy for us who're dumb XD