"This file is used for customizing some minor features of the plane by binding them to certain BMP skin.
To enable some feature, put the skin's checksum under certain tag. To find out the checksum, clear skin cache
at PaintSchemes\Cache, start the game, load skin and alt-tab back to Windows. Now cache folder has a new folder
named with long series of numbers. This is the checksum."
This tip worked for me. I use Mat Manager, so I renamed the Cache folder temporarily and made a new, empty one. Once I'd got the checksum folder and it's numbered title, I reverted to my old cache folder, put the checksum file inside and added its number to the Customization.ini