Moodle jobs

I want to make some custom changes to the Assignment plugin in Moodle - when a Tutor goes in to mark an assignment, I would like all other Tutors to be locked out for one hour.

If the marking Tutor has not completed the task within the hour, the assignment will be released and open to all Tutors again.

This is so that I can create a first come first served marking system with a bank of Tutors.

This would be a single job leading to more custom work. 

Thanks for looking.