Plugin add options to entry edition
Well I found the way lurking into source code. You can see a 

{# Give plugins a chance to add other panes here #}
{% hook "cp.entries.edit.right-pane" %}


Even though this hook is not listed in official documentation, you can access using the craft()-&gt;on() syntax, so I did this inside my plugin class :

public function init() {

    parent::init();

    craft()-&gt;templates-&gt;hook('cp.entries.edit.right-pane', function(&amp;$context) {

        // do stuff here
    });
}