Yes, there is a simple bash script that does the job. Please note that this updater is only suitable for manual updated from a shell. We're in contact with client developers to get yDNS added into their lists.
I don't see anything more about this there and I cannot think of any reason that prevents using crontab.
From yDNS FAQ:
I don't see anything more about this there and I cannot think of any reason that prevents using crontab.