Do these first:

• Install Homebrew

  # In your Mac Terminal, run:
  $ ruby -e "$(curl -fsSL https://raw.github.com/Homebrew/homebrew/go/install)"
  

  # In your ~/.bashrc, ~/.bash_profile, or ~/.zshrc (for zsh users)
  # ...
  export PATH=/usr/local/bin:$PATH
  

  $ brew doctor
  

   [full instructions]

# Mac-specific instructions
# Install node
$ brew update 
$ brew install node

Add the node directory to your PATH.

# In you shell profile (.bash_profile, .zshrc, etc.), add this line
export PATH=/usr/local/share/npm/bin:$PATH

# Install coffee (notice the dash)
npm install -g coffee-script

You now have Coffeescript installed.

# To compile a file
coffee -c cupofjoe.coffee
# Watch mode--compile a file whenever it is changed
coffee -cw cupofjoe.coffee

See also:

• Use Coffeescript in Django
• Coffeescript.org