What is the source of the XML? A different CMS...
Since the default Kentico Import / Export features uses XML files in a .ZIP. So you could have a look at that format.
Could also have a look at the Continuous Integration module and see if you can mimic that XML format.
However both have quite the dependencies and inner rules, so if this is more that a one-time developer import I'd say contact Support/Consulting and see if they can help you.