Adding Symbols to editor?

[nrep]

I've got a forum where I'd like to make it easy for users to use symbols (Ω,µ, etc...). At the moment, they need to use the keyboard ALT+### codes.

My preference would be to have these symbols selectable from a dropdown box button in the editor, similar to the way that the font size button works.

Is there an existing addon with the functionality to do this? I want to avoid using BBCode tags and just insert the proper character in to the post. If there are no existing addons that do this, is anyone aware of something similar that I could browse to get an idea?

This link looks like it may do what I'm after, but I'm not sure where to put the code:

http://stackoverflow.com/questions/14540058/how-to-display-special-characters-in-imperavi-redactor

 

[nrep]

I tried using this example with the code from above, but it doesn't seem to insert the characters as expected - nothing happens when I click the buttons (the example buttons worked fine though)

http://xenforo.com/community/resources/how-to-add-some-plugins-or-custom-buttons-to-redactor.1996/

Is this still the correct way to insert text in to the editor?

beta: {title: 'β',callback: function(obj){obj.insertHtml('β');}}

 

[nrep]

I've been working on this on and off for the past week, but haven't made any progress. Is anyone aware of a plugin that adds something like this so I can look at it for ideas?