Can I install MiKTeX using the command line?

On Windows you can use the standalone version of the MiKTeX Setup Utility:

miktexsetup --package-set=basic download
miktexsetup install

Visit the download page page to get the MiKTeX Setup Utility for Windows.

On a Mac, you simply mount the disk image file:

sudo hdiutil attach miktex-*.dmg

On Linux, the system package manager tools are command-line oriented anyway.