I have installed the Enhanced Power Kernel and I sometimes overclock the device to 800Mhz using cpufrequi or qcpufreq.
My problem is that after i cannot return back to the 600Mhz setting and I have to reboot the device. It does not accept the 600Mhz mark although it accepts the 550Mhz.
install the Enhanced Power Kernel (settings) and kernel-flasher-maemo.
lunch xterm and type : sudo gainroot
than kernel-config limits 250 600
you can replace the last 3 numbers with the frequencie you want, here is a list of the supported frequencies (for both numbers) : 125 mhz, 250 mhz, 500 mhz, 550 mhz, 600 mhz, 700 mhz, 750 mhz, 805 mhz, 850 mhz, 900 mhz, 950 mhz, 1000 mhz, 1100 mhz, 1150 mhz .
i'll suggest that you lower the voltage after the sudo gainroot command, by this command : kernel-config load lv .