Many web sites make their IRC applet available to guest users too, no only to the registered ones. At present this module sets the IRC nick name according to the Drupal registerd one. If you access the applet anonymously, without logging in, the PJIRC module sets the IRC nick name with a standard "Guest" value. Only later the guest user can change it through the PJIRC GUI.

It would be great this module would implement a sort of "PJIRC log-in page" where even the anonymous user - with no registered Drupal account - can choose its IRC nick name before joining the channel.

Maybe you could re-use code from "PHP based Login Page Version 5.0". You may find it in the official PJIRC plugins download page http://www.pjirc.com/downloads.php?p=0&c=3

Unfortunately I'm not a coder, but I can give help with graphical design and testing!