What is the easiest possible way to display inline images in a textarea?

Currently, I am trying to do a small tweak to FCKEditor. I am trying to real-time replace textarea text found between !!!sdf!!! delimiters with an image. I've tested my regular expression, which is in a function called by onchange() in the form textarea, and it works for regular textareas, but not for FCKeditor.

The function works by replacing textareas whose name I know in advance... I am horrible at reading someone else's code, so I am having great difficulty trying to find the right DOM name to replace text with -- and also, how to incorporate an onchange() function into the FCKEditor textarea.

All I'd like is a simple way to incorporate inline images into textarea (as described above). So, whether you might suggest a different inline-image textpackage or help me with FCKEditor -- Please help...