and it doesn't work by copy/pasting the desktop.ini file? Weird. This is how the file needs to look in Windows 7:
[.ShellClassInfo]
IconResource=TheIcon.ico,0
you would probably need 3 icon files (for each 'watched', 'watching' and 'not watched yet' status) and the associated 3 'desktop.ini' files. You'd then have to copy into each folder the icon file and the desktop.ini file, or you can put all 3 icon files in a separate folder and use an absolute path in the desktop.ini file like this:
[.ShellClassInfo]
IconResource=D:\Anime\StatusIcons\TheIcon.ico,0
note that the header [.ShellClassInfo] and ',0' after the filename are both mandatory, even if the file specified contains just one icon.
If you're getting your icons from a .DLL or an .EXE file that have multiple icons inside them, the number after the comma should reflect the position of the icon you want (the first icon being number 0, the second - 1, third -2, etc.).