As you may know, you can edit config/tinyMceConfig.config to modify some TinyMCE settings: commands, plugins, validElements (allowed html tags) and InvalidElements, but that's it.
Other options can't be set in Umbraco, but TinyMCE has a lot
more options.
But you can use a little hack to set other options as well:
before the last two ]] brackets of the validElements CDATA section you can insert:
Quote:", valid_child_elements :
"p/div/td[%itrans|#text]
and after that comes:
Quote:]]></validElements>
Mind the positioning of opening and closing quotes and brackets.
This makes Umbraco think you just modify the validElements option, but TinyMce will see it as a seperate configuration element (or more). Have a look at the html source of umbraco/editContent.aspx to see what it does.
You can use linebreaks within the element as much as you want to keep things clear.
The above example sets the valid_child_elements option that makes output html code more xhtml compliant (no nested p or div tags allowed).
You can however use this hack to set any other configration option listed on
http://wiki.moxiecode.com/index.php/TinyMCE:Configuration(as long as the option is ailable in TinyMC version 2, which is not the newest version).
Umbraco v4 will use TinyMce 3 and will hopefully have more elegant and standard ways of configuring TinyMCE.