This is what Gameunlimited, the authot of the mod posted in the original (
http://www.lucasforums.com/showthread.php?s=&threadid=122508) mod thread:
When you got into the Sith Academy for the first time, you have to talk to her and ask about her story. Do this like about 2-3 times, she will tell your more about herself, about the hutt slaver, etc. Once she does not tell you anymore new conversation, then you can proceed with the usual prestige gaining. At the very last part, after acquiring the sith lightsabre and the starmap, go back. You will see her and Uthar together. Then choose to side with her and kill Uthar. She will then attack you too afterwards but she will surrender after you smack her hard. Then choose the option that says like: "Mercy, you a Sith asking for Mercy?". then anything that sounds good after that point will lead to her recruitment.