Script info: http://www.userscripts.org/scripts/show/3567
Actual script: http://www.userscripts.org/scripts/source/3567.user.js
About Greasemonkey: http://en.wikipedia.org/wiki/Greasemonkey
Install Greasemonkey: http://greasemonkey.mozdev.org/
Once the script is installed, there is a test comment (and test images, obviously) on http://malesca.livejournal.com/24357.html.