Adding favicon to Control Panel

How can I add a favicon to the Control Panel?

On an older site I once added a <link rel=”shortcut icon”> tag to the file /themes/cp_themes/_shared/header.php, but it seems that in /themes/cp_themes there are now only CSS files and images.

I found this extension for EE1: http://devot-ee.com/add-ons/cm-faviconizee but I read that the show_full_control_panel_end hook that it used is no longer available. Is that correct?

Thank you.