Not directly, no.
You need to fully understand how "overclocking" works. Basically you
increase the core voltage of the processor or the bus speed to achieve the
ability to process more instructions per second. Doing so increases power
consumption (bad on a mobile device) and can limit the life of the device
(to less than a second if not done right). It's not near as easy to do in
an embedded device as it is on a PC, however you can make some headway by
getting the processor manual for the device you're working with and looking
at how the chip OEM implements both voltage and bus speed changes.
IMHO, the risk of device damage is way above the cost of a device for the
minimal gains you'll be able to squeak out of these processors. Trust me,
the OEMs are already running them as fast as they reliably can.
-Chris