SemGeshiCodeFix presents clear, highlighted code on your blog and even works in comments.

Installation

1. Download SemGeshiCodeFix plugin.
2. Unzip and extract to a local folder.
3. Upload extracted folder to wp-content/plugins folder.
4. Go to plugins tab in WordPress admin panel and activate the plugin.

To show line numbers, use following code:

$geshi->enable_line_numbers(GESHI_FANCY_LINE_NUMBERS, 5);

That is not in the plugin but you can put it in sem-code-fix.php after:

$geshi->set_header_type(GESHI_HEADER_DIV);

SemGeshiCodeFix, Plugin, WordPress Plugin, Geshi, Comments, Posts, Syntax Highlighter

Source:? Plugins Page