Just download the .zip file from the Cool Iris site, run the installer. You'll be prompted to restart Safari. Now when you visit an image content rich website such as Flickr, you'll notice a button at the lower left part of a pic which you can click to transfer to the Cool Iris wall.
You can use your mouse wheel to zoom in and out the wall, and slide the blue button at the bottom of the window to run across the wall left and right.
Definitely a thumbs up.