I have attempted to add some Delphi relevant sites to the index, and currently have configured the search to (Edited) allow hits outside only the specified sites. It would be useful to explicitly add more sites, but this is just an experiment.
Give it a try and see if you get what you expect...
You can also contribute to the configuration.
P.S. AdSense is NOT enabled, and I will NOT enable it. Ideally, Embarcadero should create and maintain the custom search, allowing it's community to contribute.
Edit: Please not that this was a very quick and dirty configuration. Given more time and experience with the CSE, it should be possible to get better results.