When you're on Telos, and you're trying to become a dark-sider, take the Ithorian's offer instead of Czerka. When you help the Ithorians and leave for the shuttle when they tell you it's ready, they'll message you and call you for help, go back to the Ithorian Compound and look in every room for Moza, the Ithorian who contacted you. Talk to him and say, "You can fend for yourself."
You'll gain a DSP, (Dark Side Point)then keep talking to him until you've reached Dark Side Mastery! (Full Dark Side bar)

This cheat has been tested and approved by Toa Nathan.