Assign tinymce to text formats
Looking through the WYSIWYG modules' code when saving the form, it implements:

db_merge('wysiwyg')
  -&gt;key(array('format' =&gt; 'full_html'))
  -&gt;fields(array(
    'editor' =&gt; 'tinymce',
  ))
  -&gt;execute();


So that's what I suspect you'll need to put into your install profile