The Canvas process is documented here [1]. You can copy paste the name+email columns from an excel/googledoc/csv file into the textbox and it will work. It is not tedious at all.
Obviously, direct upload of excel/csv would work just as well or better, if they were clever enough to pick out the name and email columns from the others.
And that is.. bad? Because it does sound tedious for the teacher. Also how do you feel about importing CSVs?