I use a laptop, so the web version, and I'm a fast typist. I prefer to do everything with my hands on the keyboard. For this reason--and because Lingvist lets me get away with it--I usually ignore accents; I just don't bother to type them in. Typing in an accent would require spending at least twice as much time on a card. (But then, I'd be learning spelling/accents much better.)
I notice special characters already have a special key, once you've opened the special characters menu. So all that's needed is a way of opening the menu from the keyboard. Maybe it already exists?