Depends on whether you have root access or not. If you have root access you can easily transfer files in and out of the box at your own risk. If not, here's the deal:
Cron tabs are typically root-owned and operated so you probably don't have access to the file. Unless you have a control panel interface to edit your cron jobs you'll have to use the command line. The exception is /etc/crontab, which is world-readable but still can only be written to by root.