Ether is a CLI the integrates with SPM (Swift Package Manager).
You can see a whole list of the available commands here
Currently, the only way is to run the following script:
curl https://gist.githubusercontent.com/calebkleveter/2e5490c76df227c510035515a49f9f01/raw/49421e072653314160bfe1c506b553805d150cb6/EatherInstall.sh | bash
Here is the Gist that is used.
A Homebrew formula is in the works (if you want to help with it, that's fantastic!).
Ether uses IBM's Swift Package Catalog to search and install packages. Add your packages to it so they can be accessed.
Ether is under the MIT license.