Tools (Download at end of post):
artDecoder.jar ===> Decodes the bin file
artEncoder.jar ===> Encodes the bin file
1. Navigate to /System/Library/PublicFrameworks/CoreUI.framework/Resources
2. Backup the SArtFile.bin file and copy one to the artTools folder
3. Open a Terminal session and "cd" to the directory of the jar files and the SArtFile.bin you recently copied over there.
4. Type the code below
java-jar artDecoder.jar SArtFile.bin artfiles/
5. If all goes well you should see a directory called artfiles in the artTools directory. There are the images you can edit to your heart's content.
6. Once editing is done open up another Terminal session and "cd" back to that directory.
7. Type the code below
java -jar artfiles/ SArtFile.bin SArtFile.new.bin
8. A file named SArtNew.bin should have been created. The file size should be around 1.5-2.5 MB. If not, then you did something incorrectly.
9. Done, you may replace the files, logout and then in and test your skin!