Run cron in WHM

No, you cannot set a cron job from WHM. If you have to set a cron server side, you will have to configure it via SSH as user "root". SSH to your server and execute:

crontab -e
This will edit the root's cronjob file at /var/spool/cron/root. Set the cronjob you like and restart the crond service.

service crond restart