Put the twitter-liveblog folder into /wp-content/plugins/
Go to the Plugins page in your Wordpress Administration area and click 'Activate' for Twitter LiveBlog.
IMPORTANT: Go to the Twitter LiveBlog Options page (Options > Twitter LiveBlog) to set your Twitter account information, liveblogging preferences and to set up Twitter update checking. You must save the Twitter LiveBlog options to enable liveblogging.