Change the XML Prolog using XMLROOT

About a month ago I wrote about using XMLType and RefCursor to rename the ROW and ROWSET tags. You can find that article by clicking here.
For the same project described in that article the XML prolog needed to include the encoding as well. Just in case you are unfamiliar with the XML Prolog, this is it:

<?xml version="1.0"?>

In Oracle 10g there is an XMLROOT function which creates the XML Prolog for you, but it doesn't allow you to add encoding to it. At least not by specifying parameters, but there is a way to do this, read on..