If you look at the ceramic that the cpu core is mounted on, you will see groups of copper lines/dots. They are grouped into 'L1', 'L2', 'L3' etc - labelled as such on the ceramic. To unlock the multiplier on your chip, just reconnect the L1 copper bridges with a pencil/silver pen - anything that conducts. Just be sure to get a good layer of graphite on if you use a pencil, and cut between the lines with a craft knife when you're done to ensure they don't touch each other. Here's links to a couple of guides with pictures. If your mobo allows you to change the mutiplier, you only need to connect the L1's, you can ignore the rest: