hi leco.
plzXoo disallows to post HTML without escaping.
This means that WYSIWYG editor is useless.
If you use any hacks about it, you can use fckxoops by editing templates *_edit.html like:
<textarea name='body' id='body' rows='10' cols='50'><{$question.body}></textarea>
<script type="text/javascript" src="<{$xoops_url}>/common/fckeditor/fckeditor.js"></script>
<script type="text/javascript">
oFCKeditor = new FCKeditor( "body", "100%", "350", "Default" );
oFCKeditor.BasePath = xoops_url + "/common/fckeditor/";
oFCKeditor.ReplaceTextarea();
</script>