There's a few pin mod for the E4300 to have a FSB of 266mhz or 333mhz and a vmod to increase the cpu voltage.
That'll take you to 266*9= 2.4Ghz or 333*9= 3.0Ghz... but with stock cooler I'd get the 266 FSB pin mod just to be safe. I have a E4300 OC to 3.0 Ghz but with AC pro 7 + AS5.
edit: with the pin mod you don't need to change anything in the MB bios.
Do you have the details of the pin mod for both 333FSB and the various VID values?
Back then I was only able to find 200->266FSB mod for E4x00 documented here