The only way you are going to be able to overclock that CPU is by raising the FSB/HT, as the multiplier is locked; it can go down due to Cool and Quiet and power saving features, but is locked from going higher than the default 15.
It also means that you will likely have to run the memory at a lower speed as its speed will also go up at the same time as the FSB/HT as they are linked. Best is to set it to the lowest value in the bios,
until you find the max speed for the CPU, and then you can raise it up to the closest speed the ram is rated for.