HTC Dash / S620 / S621 (Excalibur)

If you do a search, there is a program by Surreal Networks that will do this for you. It's a dangerous propostion though. If you overclock too high, you'll burn out your processor and even slight overclocking can cause the processor to burn out faster than it's traditional life span. Good luck. I've read numerous accounts of a smoking phone and phones bricked overtime even by doing it correctly but getting too aggressive.