Install like any other skin, extract the Ferris folder in this archive to the directory below:

Beta Users- C:\Users\YOUR USER\Saved Games\DCS.openbeta\Mods\aircraft\F-15_SMTD\Liveries\F-15_SMTD\
Stable Release Users- C:\Users\YOUR USER\Saved Games\DCS\Mods\aircraft\F-15_SMTD\Liveries\F-15_SMTD\