its not very easy, but not hard too.
only moving images is not enoght.
I made some scripts, to check what changes theme makes on system and moved those images, renaming them and checking for patch9 images, after that moved xmls (renamed) and images from those xlms (also renamed), after that corrected values (colors etc) in system files.
it was done half automated, half manually.
Glad it worked for you.