Using FS default textures in SketchUp
From FSDeveloper Wiki
This tutorial will help you convert the default FS textures to be used with Google's SketchUp. Even if you don't have a photo editor, such as Adobe PhotoShop or the freeware GIMP, you can also use ImageTool (either FS9 or FSX), which is part of the FS SDK, to help in converting the textures.