OK there is a guide, its not really for beginners, so it boils down to...
1. Disable all power saving adn turbo boost features and pick a load calibration, 1 being very stiff and one voltage constantly, 2 being a little more relax(easier to achieve stability), i prefer level 2.
2. Set voltage to fixed at first and drop it to 0.9v.
3. Boot into windows and run prime 95 or similar stresstest to test for stability for atleast half an hour. This will give you an idea of how sensitive your specific CPU is to voltage change.
4. Increase your voltage to 1.2v and multiplyer to 4.2GHz. Test thoroughly for an hour. Keep a close eye on temps with real temp or HWmonitor.