The process you outline works for updating the editor, but with PowerMessenger it doesn't work, at least with ckeditor 4.4.5. PowerMessenger will show the editor but the tokens .png doesn't show, and when you click on the placeholder it does insert into the toolbar, the token dialog doesn't work :(
Just guessing, but it seems the plugin needs a re-write...
I'll have to wait for the update to PM, I hope it isn't to far away.
Appreciate your time
** Update **
Just a note.. if error reporting is set to "on" in php.ini the mailings list does not work in ANY browser.
Trying to use PM in a test environment and found that when these are set:
error_reporting = E_ALL | E_STRICT
display_errors = On
will not let mailings list populate