i do not think this is available for the droid x. in order to over clock you need to install a new kernel. since the current recovery's for the X just bypass the current stock recovery you can not install a new kernel. i know SetCpu has the ability to overclock the droid with the stock kernel but that is also only up to a max of 800 Mghz i think.
i do not have a droid x so i am not 100% positive but from what i have heard and read about, it is not possible currently due to the locked boot loader