WordPress.org

1) Download the plugin zip file.

2) Unzip.

3) Upload the quick-reply-template directory to your wordpress plugin directory (/wp-content/plugins).

4) Activate the plugin.

5) Open up the options (In the left hand menu under Settings > Quick Reply Template)

6) Set your desired template.

7) When you click reply in the admin comments page, your reply template will be automatically inserted.