You can alter the resources in the executable with this tool:
http://www.softpedia.com/progDownload/Resource-Hacker-Download-1520.html
Just download, extract the zip file, and run the program. Go to the
file menu and open TheGuide.exe (make sure to back up the file before
this step. Just in case you accidental mess something up) Then find
the icon that you want to change from either 'Bitmaps' or 'Icons' on
the left pane, save it, modify it to your tastes, and then reinsert
the new file.