In the C6's ROFS2, you will find the default theme in the directories i mentioned:
!\Private\10207114\Import\ and !\
Resource\Skins\.
Pull them from !\NokiaCooker_X.X\Files\ and drop them back into the ROFS2 of your CFW. You can make it your default theme by making two changes to the cenrep file 101F876F.txt (the directory is found in ROFS2 \Private\10202BE9\) on lines 0x2 and 0x14. NormasInterruptor has posted a tutorial on the forum about how to do it and it is super easy, mate.