As an alternative to updating a working copy, you could check out a branch into a separate directory. You can use -d option to cvs co to put branch into separate directory.
$ cvs -d /home/cvsroot co -d hello-1-0 -r Release-1-0-branch hello cvs checkout: Updating hello-1-0 U hello-1-0/Makefile U hello-1-0/README U hello-1-0/hello.py $ ls ./ ../ hello/ hello-1-0/ $