Well, I don't think it can be edited with your Xbox. Th reason that tutorial wasn't finished is because it's kinda hard to explain editing it. It is very easy to do, but placement of where you put stuff can get congested and somewhat confusing to people that never edited ini files. So explaining it in easy terms is hard to do.
[edit]: ok, I finished it.
Here is another tutorial on that
http://www.dickweed.org/evox_doc.htm
It deals with all the aspects of the ini file and can be complicated for anyone new to the scene. My tutorial will just be on inserting links to files on your HDD and stuff like that.