I had asked Merlyn about that a few days ago and he had made an off hand suggestion that you change the shell for cron from vi to Perl. I could not do it in my case but you might be able to do something like that.
in reply to Using perl as a cron script?
As far as adding and removing entries you will need to have access (A login) to the cron you want to edit. Generally every login account has a crontab that can be listed by crontab -l or edited by crontab -e. There is a way for the administrator (root) to add the crontabs to a group that you are a member of then you could use Perl to edit the flat files and then the admin would need to do a crontab -e then a write to update the crontab. There is no easy way to do it. I am currently developing a Tk interface that will allow you to edit any cron but you will still need to know the password for the account you want to work with.