To overclock thats in the CELL menu, ''Adjust CPU base Frequency'' should be at 133mhz stock.
I'm guessing the CPU voltage control will be under the ''Green power'' menu, and then ''CPU phase control'' take that from auto to manual to set the voltage.
With all that said, if you are overvolting your CPU you shouldn't be using the stock CPU cooler. Do you have an aftermarket one?