You could try the Google CSE plugin.
I’ve tried both the plugins you mentioned above, but I couldn’t get them to work in the way I wanted, so I settled with the Google CSE plugin, and I’m rather happy with how it works.
It actually serves the results from your Google Custom Search Engine via the WordPress search listing, which means there is no need to customise your theme or search box. Because of this special integration, you also need a Google API Key (as well as the CX from your Custom Search Engine).