// This gives us /updateSites.xml
URL url = Activator.getDefault().getBundle().getEntry("updateSites.xml");

// This gives us /home/username/.../updateSites.xml
URL absoluteURL = absoluteURL = FileLocator.resolve(url);

// Now create the file
File file = new File(absoluteURL.getFile());

// The file reader
FileReader reader = new FileReader(file);

// Now create the memento
IMemento memento = memento = XMLMemento.createReadRoot(reader);