This archive contains files that are intended to overwrite files from other mods in order to patch the unique shadows into them. For that reason, you may want to make a back up of the Data Files/Meshes/MOG_v4 and/or the Data Files/Meshes/AS folder prior to unpacking the archive. Additionally, if you later decide to install one of those mods, you will have to choose not to over-write any files, or re-install this mod over the top of them again.
Once you have made any back-ups that you desire, simply extract the archive into the Morrowind install location. The Data Files folder within the archive should match up with the one in the Morrowind folder. Choose yes to overwrite any files that this mod patches, or no if you do not wish to alter Better Beasts or Mog*Mod to add unique shadows to them.
Because the mod simply writes new versions of existing files, there is no need to enable any plug-in file. Just start the game and enjoy the new shadows!
To uninstall, restore the back-ups you made of the Data Files/Meshes/MOG_v4 and Data Files/Meshes/AS folders, and then delete the following files:
Data Files/Meshes/xbase_animkna.nif
Data Files/Meshes/b/b_n_argonian_m_skins.nif
Data Files/Meshes/b/b_n_argonian_f_skins.nif
Data Files/Meshes/b/b_n_khajiit_m_skins.nif
Data Files/Meshes/b/b_n_khajiit_f_skins.nif