Change CPU Speed With WiMoSpeed
If you want to be able to change the clock speed of your Windows Mobile device CPU, check out XDA forum member iwfratz‘s application, WiMoSpeed.
The app manipulates the values WM uses for clock control, so it works reliably on battery and AC without any scripting or active components.
It depends on CPU-hardware, as well as radio and OS ROM since the dev could not get WM to switch the clock reliably on request. So, WiMoSpeed switches the clock registers itself upon setting a new speed.
For more information and to download the cab file, head on over to the application thread.