TinyMCE is not included in the inputEx distribution !
Download it on http://tinymce.moxiecode.com/ (tested with version 3.3.7) and install it in lib/tiny_mce
Use the following code to create a basic inputEx TinyMCEField.
Test for setValue/getValue using the TinyMCEField.
Use the following code to create a SimpleEditor widget
You can have access to all the tinymce config options through the "opts" attribute. Check out the TinyMCE examples for all options.