That could do it:

    npm install -g grunt-cli 

@scottgonzalez, by bringing the actual commands from their documentation, do you think we also would need to bring some other notes, eg: "You may need to use sudo (for OSX, *nix, BSD etc) or run your command shell as Administrator (for Windows) to do this. Also make sure that git is installed as some bower packages require it to be fetched and installed."?