Which type of CAM. are you talking about....??
Theoretically it should be possible with the newer Euro CI CAMs but it is not done.
With the older CI CAMs, flashing can only be done via computer (PCMCIA interface).
With the original CA CAMs (no slot; as used in D-Boxes & Nokia 9200/9500) it is only possible be removing the flash chip. Indeed this is the only way used to update the new Euro CI CAMs too.