Not completely sure what you want to do, however, you can definitely load data from .xml file from external source using the following code:
ListView {
dataModel: XmlDataModel {
source: "path/to/yourxmlname.xml"
}
}
If you consider to access external data from c++, you can use the following code:
QFile file(QDir::currentPath() + "/path/to/your/file");
if(!file.open(QIODevice::ReadWrite)) {
qDebug() << "error opening file";
return;
}
file.readall();
file.close();
Then you can pass the data retreived to qml following the instruction:
http://developer.blackberry.com/native/documentation/cascades/dev/integrating_cpp_qml/index.html