Disqus is great. It's a full featured cross-site comments free management system. I have an account on it, so I wanted to use disqus instead of the typepad comments system.
"Easy enough" I said to myself : there is a dedicated page to help you install Disqus in Typepad. This includes adding a new "Embed your own HTML" module in your blog content, and copy-pasting a Javacript snippet in it.