Update – The latest version (2018) is discussed here and the bookmarklet itself is https://www.onlinesales.co.uk/tools/tools/bookmarklet-serps.php.
This video is using a version from 2009:
I used to have the code here for you to inspect and adapt, but several sites have stolen the code (which is naturally and automatically covered by copyright) and re-branded it as their own. :-(.
Code and contents © Liam Delahunty, 2009 – 2019.