This is interesting.
The younger dooku was done only with PS actions.Meaning I didnt have to select the hair by hand or erase skin-hair blending problems. Basic masking was done to separate the new head from the rest of the comp and the younger face was done with no stamp or clone too. I just touched for fun with liquify his face so he is smiling ironically..
In other words with some careful management of tools this can be done in motion. I basically took the theory of the FX team that made Surrogates.
-Angel