The easiest way to add your iCal calendars to iPod's Calendars list is to use iTunes, but you can manually add it if you want. To find out how to sync calendars with iTunes click here.
Update iPod
Update your iPod with the latest software for your model.
Export your calendar in iCalendar format
Copy the iCal (.ics) file to iPod
Days with events have a bullet (·) in the day cell. Scroll through the calendar and select a day to view its events.
Events with alarms you create in iCal also work on your iPod.
Related documents
61707: iPod 1.2: Calendar Events and To Do Items May Not Appear Immediately
61754: iSync: About synchronizing data with iPod