For the information of anyone else looking to do this, you can do it in the GUI: Add it to the search bar In the search bar dropdown, click "Manage search eng

For the information of anyone else looking to do this, you can do it in the GUI: Add it to the search bar In the search bar dropdown, click "Manage search engines" Select DDG and set a keyword. I use "d". Then, search using e.g. "d Hacker News"