[Zope] Date utility for Zope (V2)

I am looking for a standard way (from a python script in Zope) to define and manipulate time intervals for periodic events. I need to define things like every weekday at 8 am, the 2nd day of every month at 8am, every weekday at 8am, 10am and 3pm in addition to easy things like everyday at 1pm. Does such a standard exist - perhaps with a library to manage the conversion to real times? On another forum this http://labix.org/python-dateutil was suggested -- it looks to be close to what I was thinking -- but I am not totally sure how I can use it in Zope (a level of incompetence issue no doubt). Is there something else Zope(not Plone) ready? Or alternately how would I use this in Zope?