This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
SAX is just for parsing XML - you can't use it to change XML (unless you want to write code that recreates the complete XML file).
DOM can be used, as could any of the other XML object models (XOM, JDOM, dom4j). See e534 to e538 for examples of how to work with attributes in DOM. See this for how to obtain a DOM Document from an XML file in the first place.