I'm not sure but i guess you could simply open it up with your standard editor and rewrite the passages that you want to change.
Even if this is not the case, you'd only need to download a special editor for xml files and open them that way, the interface would be similar to that of the standard editor.
As long as the format would be similar to the way Darvin described them, all you had to do was to change a set of expressions which you could look up at the wiki. As long as you have the heart to do it, this should be no problem for you as it's really easy, even for someone that never programmed
