You cannot edit the CD image file directly. You must unpack the image file to reveal the individual files.
The MDF file is a CD image file, and MDS is the corresponding catalog file.
Open the MDS file in UltraISO, you will then see the CD contents inside it.


The read this thread to see how to use NavTweak:
http://www.xoutpost.com/navigation-sy...-navtweak.html