Ok, figured this one out on my own... Should have done this originally in the light of day instead of late at night and falling asleep.

The main theme files are just plain old CCP remote files. So without even taking apart any VFDs, if someone wants to create a re-usable theme, simply copy one of the existing ones, give it a new filename, enter than name into the ini listing of themes so it will show up as a theme in CCP and then load that file into CCP and start modifying it.

You can specify images from disk and then simply include that folder along with the theme if you're giving a copy to someone else.

Doh!