This you tube of a luthier (I believe in Swedish with English subtitles) shows the luthier sharpening a chisel with a Tormek (at about 2 min, 20 sec and toward the end). He uses a mirror to check his progress.
http://www.youtube.com/watch?v=TryJtirFFME
Ken
http://www.youtube.com/watch?v=TryJtirFFME
Ken