This article will show you how to insert a <link> tag in the header of the html when in the "Edit HTML" tab of Blogger/Blogspot. The example I give involves using the prettify library.
The background behind why I want to do this
The first order of business is to include JQuery:
Next we insert the CSS file into the <head> element:
Now we add the Prettify library.
<script src="http://your.site/tools/libraries/prettify.js"> </script>
Finally, at the very bottom of your page you need need to call prettyPrint()
Update: Ok I give in. JQuery is overkill. See my new post for a neater way to do this.