First you need to download and install the perl module
Mac::AppleScript.
Unstuff the folder and open terminal, then 'cd' into the folder you just created. Type 'perl Makefile.PL', this should come back with
"looks good". Then type 'make', after that type 'make test' (you can skip this) and lastly 'make install'.
With that done you can download and install the iTunes2irssi script. Put it in irssi's scripts folder (~/.irssi/scripts). To
accomplish this you can either use the 'mv' command "mv ~/Desktop/iTunes2irssi.pl ~/.irssi/scripts" or use the 'Go to folder' command in the finder.
If there is no scripts folder you can go ahead and make one. Alternatly you can make another folder inside scripts called "autorun". When
you launch irssi any scripts inside the autorun folder are automatically loaded. otherwise you load a scrip with the "/script load itunes2irssi.pl" command.