how to install old version of express.js

How do I install the right version of express and do I have to uninstall 3.x before I install 2.x?

This is the tutorial I am trying to test: http://psitsmike.com/2011/09/node-js-and-socket-io-chat-tutorial/

I used this package.json:

{
     "name": "mukhin_chat",
     "description": "example chat application with socket.io",
     "version": "0.0.1",
     "dependencies": {
        "express": "2.4.6",
        "socket.io": "0.8.4"
     }
}

and used the following command:

npm install -d

When I run the app I still get the question: ... are you migrating from Express 2.x to 3.x ...