The Subject Watcher script allows you to be notified (via sound or text) when a certain phrase appears in someone's tell on the server. Here is the information you need to add the script:
import jregex.*;
String subject = "hello world";
String soundFile = "C:\\tmp\\sound.au";
Pattern pattern = new Pattern(".*\\b"+subject+"\\b.*", "i");
if (pattern.matcher(message).matches())
playSound(soundFile);
Code for textual notification (in the console):
import jregex.*;
String subject = "hello world";
Pattern pattern = new Pattern(".*\\b"+subject+"\\b.*", "i");
if (pattern.matcher(message).matches())
appendLine("\""+subject+"\" is being discussed");
In both pieces of code, replace the subject's value for your own phrase. In the first example, also replace the value of the sound file to some file on your disk.