I wanted a different editor for TinyD (from http://tinymce.moxiecode.com/) to make it easier for my users to add content. I liked the TinyMCE editor that other CMs used and found that it's easy to get running.

I'm sure an expert XOOPS developer has a better way than this, but
to just get things running:
1) download TinyMCE and copy its jscript directory to /common
2) modify include/cp_functions.php around line 68 to insert the following TinyMCE jscript lines; it's explained in TinyMCE's manual.

<!-- tinyMCE -->
<script language="javascript" type="text/javascript" src="/common/jscripts/tiny_mce/tiny_mce.js"></script>
<script language="javascript" type="text/javascript">
tinyMCE.init({
mode : "textareas"
});
</script>
<!-- /tinyMCE -->

The issue I don't understand how to fix.
-- When you save the TinyD content, the content is saved to the database, but doesn't reload the page -- you have to manually reload.