Node和npm均已安装并且是最新的，但是在尝试安装coffeescript时始终出现此错误。我还是编程新手，所以任何建议都将不胜感激。

test-macbook:~ Test$ npm -v
1.1.0-3
test-macbook:~ Test$ node -v
v0.6.8
test-macbook:~ Test$ npm install -g coffee-script
npm http GET https://registry.npmjs.org/coffee-script
npm http 304 https://registry.npmjs.org/coffee-script
npm ERR! Could not create /usr/local/lib/node_modules/___coffee-script.npm
npm ERR! error installing coffee-script@1.2.0

npm ERR! Error: EACCES, permission denied '/usr/local/lib/node_modules/___coffee-script.npm'
npm ERR! 
npm ERR! Please try running this command again as root/Administrator.
npm ERR! 
npm ERR! System Darwin 11.2.0
npm ERR! command "node" "/usr/local/bin/npm" "install" "-g" "coffee-script"
npm ERR! cwd /Users/Dylan
npm ERR! node -v v0.6.8
npm ERR! npm -v 1.1.0-3
npm ERR! path /usr/local/lib/node_modules/___coffee-script.npm
npm ERR! code EACCES
npm ERR! message EACCES, permission denied '/usr/local/lib/node_modules/___coffee-script.npm'
npm ERR! errno {}
npm ERR! 
npm ERR! Additional logging details can be found in:
npm ERR!     /Users/Dylan/npm-debug.log
npm not ok