1.6.41 is an update to the Aether II mod, also known as the Summer Hotfix, which was released on August 9, 2014, it nerfed Zepyhrs to fix complaints of them being too overpowered, bug fixes, and added the addition of companions and new items.
Finally, click Install at the bottom right of the launcher after you select Aether II (1.6.4) mod from the list on the left. The launcher will handle everything else!
If you are using forge run the Forge Installer.Download the Aether II and Guilded games utility for 1.6.4.Windows Vista and up: %APPDATA%/Roaming/.minecraft/bin/Windows XP and below: %APPDATA%/.minecraft/bin/
If you are using the aether II launcher run the file launcher-start.jar.You will be asked for your mojang e-mail and password. Then press play. The aether II will begin downloading and then minecraft shall run with the aether installed.
As the title says, this article will help you install Ether's Unbelievable Shaders for Minecraft versions 1.6.2-1.6.4. I'm sure a lot of you know what this does, but if not, here's a little refresher: 2b1af7f3a8