One quirk is that I use the NSView that I subclass purely to be able to position the program generated WebView using Interface Builder, and the actual NSView doesn’t draw itself. If you want to make any changes, then editor.html and mceconfig.js are the files used to create the WebView and embedded textarea, and MCEditor.h/MCEEditor.m are the class files. To use this in a project, drop in these four files, and add the tiny_mce folder into your project resources; the folder should be at the same level as the html and js files. It should be ok to replace the tiny_mce folder with an updated version.
Xcode can sometimes get confused with .js files, so you should drop mceconfig.js onto “Copy Bundle Resources” in the application target, and remove it from the “Compile Sources” build phase.