Yep, still done by ear. There may be a digital reference for A440, but tuning for temperament involves listening for beats between intervals. No two instruments are the same, and there's no good way to do it with a tuning device, you have to listen for beats, and literally count them. Then, tuning for stretch, which corrects for cumulative inaccuracies caused by temperament tuning, you have to listen to tune for partials. Pretty tricky stuff, and yes, the only way is by ear.