[Zope] xmDateTime Substitute for Zope?

An application has need for the RelativeDateTime() feature of mxDateTime. However, if one tries (in a python script)... from mx.DateTime import * .. Zope returns an error message indicating that the attempted import was unauthorized. Does anyone know of a substitute? Or how the problem could be circumvented? What I'm really looking for is a way to calculate the date 20 months from now(). mxDateTime has a handy feature for that, which would simply be: LaterDate = now() + RelativeDateTime(months=+20) Would this be possible via an External Method or is there a way for Zope to do the arithmatic without needing mxDateTime? Thanks in advance, Ron