Here's a little something I originally cooked up for the users of Topogigi ROMs, but works on any ROM which has the Andrev OC daemon installed.
It's an app with which you can adjust the OC-daemons settings, and apply them immediately.
Usage should be self-explanatory, ask in this thread if you have any questions.
WARNING: Remember that you may get an unstable phone if you overclock too high. Not all phones can handle high overclocks, especially not over time. I advise you to never go above 1216Mhz, even if it seems stable at higher frequencies.