Split a TOC

Hi list how do I do this, for example if Have:

<tocentry page="index.xml" id="index" dir="index/" filename="index.php">
	<tocentry page="2.xml" id="two" dir="two/" filename="two.php">
		...
	</tocentry>
	<tocentry page="3.xml" id="three" dir="three/" filename="three.php">
		...
	<tocentry>

</tocentry>


How can I then get Docbook to output all sub-levels and all indexes  
to a separate TOC? For example producing something like:


<ul id="LevelOne">
	<li>index</li>
</ul>
<ul id="LevelTwo">
	<li>Two</li>
	<li>Three</li>
</ul>

Many thanks