I created a custom search engine (string) in Preferences invoked with a hotkey. Now from the address bar I type the hotkey plus the search terms, and the search is performed when I hit the ENTER key. I chose the hotkey 'f' . I couldn't use 'g' as that has already been taken by Opera.
Here is the search string I am using for the English (American) version of Google.
My work computer defaults to the Brasilian version of Google unless I use the 'f' hotkey from the address bar. If I use the 'g' hotkey I get a Brasilian Google search.
If you don't want to use Google, there are other search strings that will work. You might get them to work by right-clicking on the search bar of your chosen Search Engine and choosing "Create Search Engine..", but that didn't work correctly for me for changing versions of Google.