
Ok here some things which would be handy:

Upload the "sounds" folder outside the cgi-bin of your Board or you don't be able
to hear anything.
You have to set the paths into the admin panel in "Board Settings/Preferences".
You have to enable there the popup and sounds options too.
You have to overwrite the old InstantMessage.pl with the one in the Zip-File,
but before you do that make a backup of your old file.
So if you want to remove the mod you have to overwrite the new one with the old
one again.
Every User has to enable the Popup/Sounds into his Preferences in his IM Box.