Upload everything (keeping the directory structure) to the /wp-content/plugins/ directory.
There should be a /wp-content/plugins/qtranslate-separate-comments directory now with qtranslate-separate-comments.php in it.
Activate the plugin through the 'Plugins' menu in WordPress.
Go to the Comments section in WordPress Dashboard and set the appropriate language for all of your comments(you can use the "Bulk Set Language" button after selecting some comments and the right language for them).
Requires: 3.3.2 or higher Compatible up to: 3.5.2 Last Updated: 2013-5-28 Downloads: 2,529