Idea for an Event Editor

What you want is here. Search for "EventDisasm.zip".

It is essentially what you are looking for, without the editor part. It includes the descriptions as well as the hex, so all you will need to do is open up an editor and make your changes. And... if you know that super-fantabulous B2 command, you have practically unlimited space to work with. It will also serve as a gateway drug into hex editing in general... once you get hooked, it's hard to stop.

I typically just use HxD.