How do I set it up? Go to the LibraryLookup Bookmarklet Generator.
Our base URL is http://lib.sou.edu. (The base URL for Summit is http://summit.worldcat.org/.)
Name it as you see fit.
Click on "Build your own LibraryLookup bookmarklet!"
And voila, you've done it! Now follow the instructions to drag the link onto your toolbar.