I'm currently working on a project that requires the ability to have internal css, as there will be some content that will be unique and inline css is not sufficient. I will also need the ability to add custom javascript on a page by page basis. I realize that this isn't completely ordinary,neither is the content of the site. Currently, I am using SS3 and have followed the instructions to do the following:

HtmlEditorConfig::get('cms')->setOptions(array('extended_valid_elements'... etc. into the mysite/_config.php

unfortunately, this has had no effect. Is there anything that I am missing? I would be happy to provide additional information if necessary.