Are you sure that you have correctly installed kernel-power package as it was described in instruction? You may use cpufreqUI or qcpufreq to set new limits easily and use conky to monitor current cpu frequency. Keep in mind that frequency is controlled by ondemand concept and switches dynamically between lo and hi limits. cpufrequi allows to change concept to userspace (fixed freq on your choice). Please, give more detailed information about your problem.