Instructions and the links for the downloads can be found here. You will need to rebuild the installer to work with a MacPro 1,1 and to use the 32bit EFI translator.a video card capable of running the latest OpenGL and with at least 512MB of video memory - 1 GB is better.a copy of the Mac App Store El Capitan installer.

To get El Capitan to install on a MacPro 1,1 you need several things: You will have to find a fully Mac Compatible video card if you want boot screen graphics. You won't be able to see your selections once booting and holding down the OPTION key right after the chime. This is only an issue is you have to boot into a separate hard drive or a Bootcamp partition. There are a lot of PCIe graphics cards out there that will work in a MAC but they don't boot EFI which essentially means you will get a black screen during boot up until the boot has completed - then the video card will switch on. I suggest one with at least 1 GB of video RAM. It even includes a script that will check and fix the bootloader each restart which means you can install system updates without having to repatch your system each time. It is correct about the 32 bit EFI on these systems but there is a workaround with a re-written bootloader for the MacPro 1,1 that will enable you to run El Capitan (last OS before Sierra) flawlessly on your Mac Pro. It sounds like you have a mac pro 1,1 like mine with Quad core 2.66GHz processors.

Instal the new version for mac Avatar: The Way of Water