I always hate it myself when I ask for something, people begin to give me all kind of stupid alternative suggestions that do not actually match with what I have asked for... But I don't know what your purpose of this feature is, so maybe this plugin helps: key flasher
http://shoutbox.menthix.net/showthread.php?tid=63303
You can disable toasts in Messenger itself, and set this plugin to flash your keyboard led when in any status you wish. You can also make it beep if you like
Sorry if this is no use for you. Would like to hear if this helps or not