For the basics, look at the instructions for student checkins
Instead of checking out a single user directory, you want a copy of the whole repository
cvs -d /afs/umbc.edu/users/o/l/olano/pub/class checkout -d grading-directory .
cd grading-directory cvs update -d -D 'date' */assignment
Or to get a single student's late assignment
cd grading directory cvs update -d -D 'date' student-login/assignment
The date format is 'mm/dd[/yy] 24-hour:time timezone'. For example an assignment due September 11th, you might use '9/12 0:00 EDT'.
Edit file containing grade and comments (e.g. grade.txt) in the assignment directory for each student. Then check in these files
cvs add */assignment/grade.txt cvs ci -m "assignment X grades"
List of all CVS commands
Help on any one CVS command
cvs --help command
General CVS manuals, downloads, etc.: www.cvshome.org