As far as it relaying to irc... I recently did that.

Where it says
/*
      This gets called on a msg in the guildchat with the command
    */
    function gc($name, $msg)
    {
        $this -> bot -> send_gc($this -> process_command($name, $msg));
    }
Add this right after the send_gc part
$this -> bot -> commands["tell"]["irc"] -> irc_send_local($this -> process_command($name, $msg));
If you are using the cron part (having a quote relay every x number of mins) you can add it there too.. but how I have it it shows a different quote in irc than it does in-game since it grabs a random one for each. But here is the change I made... Change this:
/*
        This is cron()!
    */
    function cron()
    { // Start function cron()
        if ($this -> nextquote < time() && $this -> settings['AUTO'] == 1)
        { // Start if()
            // Set time of next quote output.
            $this -> nextquote = $this -> nextquote + ($this -> settings['INTERVAL']*60);
            switch ($this -> settings['CHANNEL'])
            { // Start switch
                case "GC":
                    $this -> bot -> send_gc($this -> send_quote(-1));
                break;
                case "PGROUP":
                    $this -> bot -> send_pgroup($this -> send_quote(-1));
                break;
                case "BOTH":
                    $this -> bot -> send_gc($this -> send_quote(-1));
                    $this -> bot -> send_pgroup($this -> send_quote(-1));
                break;
            } // End Switch
        } // End if()

    } // End function cron()
To this:
/*
        This is cron()!
    */
    function cron()
    { // Start function cron()
        if ($this -> nextquote < time() && $this -> settings['AUTO'] == 1)
        { // Start if()
            // Set time of next quote output.
            $this -> nextquote = $this -> nextquote + ($this -> settings['INTERVAL']*60);
            switch ($this -> settings['CHANNEL'])
            { // Start switch
                case "GC":
                    $this -> bot -> send_gc($this -> send_quote(-1));
    $this -> bot -> commands["tell"]["irc"] -> irc_send_local($this -> send_quote(-1));
                break;
                case "PGROUP":
                    $this -> bot -> send_pgroup($this -> send_quote(-1));
                break;
                case "BOTH":
                    $this -> bot -> send_gc($this -> send_quote(-1));
                    $this -> bot -> send_pgroup($this -> send_quote(-1));
                break;
            } // End Switch
        } // End if()

    } // End function cron()

good thinking on that, no clue why I didn't think of that minor change.

As far as calling it from IRC, that would take some mods in the IRC.php file.  You can see the irc_is and irc_online functions as a reference for it.