frequencies and voltages are in kernel in file
arch/arm/mach-omap2/omap3-opp.h

i was able to overclock the phone to 800Mhz, boot it without problem and using it for 5 minutes
but i am hunting longer battery life instead of speed, so i am running kernel with 125Mhz enabled
(125,250,500,550,600) instead of (250,500,550,600)