Sorry, no way. The FSB is not adjustable. It's locked at either 100 or 133 depending on the CPU installed. There's also no memory ratio setting in the BIOS, which you would need as well. Basically if you install a P4 Willamette or a Northwood (A type) the memory runs at DDR200, and at DDR266 with a B type (533) cpu installed AUTOMATICALLY.
Sorry...no substitutions.