Hello,
We've produced a drop-in TinyMCE 3 based replacement WYSWIYG editor for HTMLArea in Moodle 1.9. This modification will overwrite the older existing TinyMCE editor with a newer version and only requires a single core file, /lib/setup.php, to be changed. After installation any user configured to use HTMLArea will now use TinyMCE to input HTML.
PHP 5.1 or later is required for correct functionality. Failure to meet this criterion may cause your Moodle site to stop loading. These changes have only been tested against Moodle 1.9.12 stable, but should work with older and newer versions of 1.9.
The latest stable version may be downloaded here: http://www.webcourseworks.com/sites/default/files/moodle-tinymce.zip. Installation instructions are provided inside of the zip file.
Development may be tracked on github: https://github.com/WebCourseworks/moodle/tree/tinymce. Installation instructions are provided here: https://github.com/WebCourseworks/moodle/blob/tinymce/readme-tinymce.md. Patches are welcome.