SyntaxHighlighter

Dashboard > Design > Add a Gadget > HTML/JavaScript

Include

shCore.js
shBrushPerl.js
shThemeDefault.css

Add script

<script> 
SyntaxHighlighter.defaults['light'] = true;
SyntaxHighlighter.all()
</script>

Add style

<style>
.syntaxhighlighter {
padding : 2px 3px;
line-height : 1.1em;
font-family : monospace
}
</style>

References:
alexgorbatchev.com/SyntaxHighlighter/manual/installation.html