Syntax Highlighting your Blog with highlight.js
Go to Software Maniac's download page. Turn off the languages you're not interested in. Check the checkbox for Smalltalk. And hit the download button. You'll get a new customized highlight.js file for your efforts. You need this customized version because it doesn't support Smalltalk in the stock version.
Then just insert that javascript file into your page, and start using it. If you need directions for Blogger specifically, they're in Travis' post.