Since you already have your plugin working:
The easiest way to do this is to edit the file "/vb/ckeditor.php". Find the class::method "SetToolbar" (around line #258) and add your ckeditor plugin reference directly to the toolbars. You can easily rearrange the toolbars in this class::method.
If you need to do this via a plugin you can recreate/rearrange the toolbar arrays and use the hook: '
editor_toolbar_set'.
Example: (for "/vb/ckeditor.php").
PHP Code:
// Hopefully, I did not over simplify.
$toolbar[] = array('Bold', 'Italic', 'Underline'); //original
$toolbar[] = array('Bold', 'MyCustomPlugin', 'Italic', ' Underline'); // new - positioned
Sincere thanks for all the 'pioneers' that indirectly (years ago) took the time to point me in the right direction via your articles and posts. You guys/gals never get praised enough: @Cellarius, @Nerbert, @Lynne, @Kh99. If I missed anyone I apologize.