For this to be possible you must have a Passport, that is, an account in Hotmail.
Step 1 - Go to http://settings.messenger.live.com/applications/WebSettings.aspx
Step 2 - Log in with your Passport
Step 3 - Check the checkbox to let people see your Messenger status on sites and send messages to you. If this option is not checked, your status will always be OFFLINE.
Step 4 - Click Save
Step 5 - Click the Create HTML tab and choose your visual and functional preferences.
Step 6 - Copy the HTML that will be generated and paste it into the HTML Code Online Service via MSN in your Control Panel> Settings.