well, if you're using mirc, it's built-in.
just go to file->options->connect->identd
then check the box that says "enable identd server"
in the "username" box, put your username.
in the "system" box, put "UNIX"
in the "port" box, put "113"
i have all the other boxes checked, too. not sure if you need them checked, but that was the default, and it works.
hope that helps.
Paul