Edit: Guess babyboy808 beat me to it,
Assuming that you're hosting the blog yourself, or at least have access to the template code...
...as far as I'm aware, shouldn't need to use a plugin or widget.
It's entirely possible to install it directly, like they say on the analytics site (that is, put it into the footer above </body>).
Do this:
-Go to 'Presentation'
-Go to 'Theme Editor'
-Click 'Footer'
-look through the code on the left for </body>
-Paste code directly above </body>
It can take a few moments for analytics to figure out that it's there, so if it doesn't work right away, give it a few minutes and hit check again.
