Firefox: Install the Greasemonkey extension. After that, clicking the link to the script should prompt you to add it.
Chrome: Install the Tampermonkey extension. After that, clicking the link to the script should prompt you to add it. You can also install it without Tampermonkey by saving the script to your computer, going to your extensions page, and dragging and dropping the file into the Chrome window.
Midori: Enable the “User Addons” extension. After that, clicking the link to the script should prompt you to add it. More details.