did you make the project open source, I would like to take a glance on it.
This post is pretty old. It's using Ext 2.x. The code probably won't be too worthwhile, but if you're curious about CakePHP and ExtJS integration let me know, that's what I work with now. It's super simple once you setup a few things!
I'm currently working on a project to integrate ExtJS and CakePHP (http://banchaproject.org) and I'm always curious what else I could add to make it more powerful. So I'm happy about any thing you can tell me of how you are integrating them