[Zope] date format in other time-zone

Is it possible to format a date to GMT or in general in other timezone other zone? I have read through the Quick reference but do not have answer. The ToZone(z) is listed there under DateTime. But How can I use that? Moreover, how can I make date-time calculate : adding 3 days to current time. Add 2 minutes to current time, etc. Rgs, Kent Sin