How to play with acronym under Tinymce

Hello,

I can’t find how to use acronym with my WordPress setup… I do not see the right button under Tinymce and cannot find any plugin to add such fonctionality. Okay, I find some but they all seem to be based on a acronym replacement philosophy (you have a to edit a list of acronym and the plugin will do the code for it). I would like to see a plugin where you can create acronym for each post when you want by a simple but effectiv and unique set of caracters. The goal is to fin a special set of characters that a plugin will automatically identify and manage… E.g. :
WP_(WordPress) will be replaced byt the right acronym code.