Small changes to source XML

Forgive me for seeming ignorant, but I certainly am in this case.  I want to
mostly copy all of my source XML to the output XML, with some small changes.
For instance:

<root>
	<a ID="74">
	<a ID="75">
	<a ID="76">
</root>

I want this output:

<root>
	<a ID="0">
	<a ID="0">
	<a ID="0">
</root>


What is the best way to do this with a lot of XML without using xsl:element?