Desperate for an intelligent Wysiwyg editor - Mail Merge

Hi

This is my second post on this, I'm getting desperate now.

I have been tasked to build an cross browser mail merge template builder, for this I obviously need a WYSIWYG editor. But I need some extra functionality. I need the abilty to drop 'text fields' into the text... this would show as normal in the text box however would be read only. For example, see below:

"Dear [* Client Name *],
Welcome to my text project blah blah blah"

In the above example the user would be able to edit all text except from the text inside the square brackets.

An example of this can be found at:

    http://bin.textcontrolasp.com/TX13.Server.Browser.Basics.CSharp/step4.aspx

The problem with this one is that it is ActiveX and therefore not supported by Firefox. Another good example is:

    http://www.interspire.com/devedit/demonx/demo4.php

Unfortunately this is written in PHP and therefore I can't integrate it into my ASP.NET application.

I also have toyed with the idea of extending an editor like cute editor, however the javascript reference material is very basic, and the source code has been scrambled.

So the questions are: do you know of an ASP.NET editor which fits the above? Or of an ASP.NET editor which has decent documentation on the javascript API? Not just the very basic info.

Thanks for reading, hope you can help!