For example, right-click the field on dictionary.com and declare that "d foo" in the address bar will look up "foo" using that form from now on.
It's not quite as easy as right clicking the search box in Chrome, but you can still do it by right clicking the address bar and going to Edit search engines. You can manually add named searches there. After the first time you search on certain sites, it will automatically add them as named searches (I noticed this with Amazon, eBay and Wikipedia--you'll see them show up in the Edit search engines area).
It's not quite as easy as right clicking the search box in Chrome, but you can still do it by right clicking the address bar and going to Edit search engines. You can manually add named searches there. After the first time you search on certain sites, it will automatically add them as named searches (I noticed this with Amazon, eBay and Wikipedia--you'll see them show up in the Edit search engines area).