CVS has a wiki manual available, which seems to be the best reference.
Getting old files from CVS
To extract a single copy of an old file from CVS, use the following command in the CVS controlled directory:
cvs up -p -r 1.1 filename.cpp > ~/filename-old.cpp
- The -p option tells CVS to output the file on the standard output stream, instead of attempting to overwrite the old file.
- The -r option specifies the revision to use, in this case 1.1
To remove all tags from a file:
cvs up -A