I've compiled a binary for setting the clock speed (from 200 to 430 MHz). Copy it to local/bin and execute it with cpu value; for example, cpu 360
Click!(sourcecode included)
Source: http://www.gp32x.com/board/index.php?/topic/48910-is-there-an-app-for-adjusting-clock-speed/page__view__findpost__p__744350