After installation simply add an HTML plus block and begin editing.
The add-on uses the Codemirror Javascript library which is released under the MIT license.
The Codemirror instance is initiated in the file form_setup_html.php. Options can be set by editing this file.
Full Codemirror documentation is available at http://codemirror.net/2/doc/manual.html
To change the quicklinks edit the PHP at the top of the file form_setup_html.php file.
Currently customising this block requires some PHP and Javascript knowledge. I will hopefully find a more user friendly way of customing this block in future.