As of version 3.9.4, the “How to Install Command Line Tools” says:
One may add CMake to the PATH:
PATH="/Applications/CMake.app/Contents/bin":"$PATH"
Or, to install symlinks to ‘/usr/local/bin’, run:
sudo "/Applications/CMake.app/Contents/bin/cmake-gui" --install
Or, to install symlinks to another directory, run:
sudo "/Applications/CMake.app/Contents/bin/cmake-gui" --install=/path/to/bin
The middle option worked perfectly for what I needed: installing an older version of Swift using swiftenv.