iCal: How can I define a custom sorting of reminders?

Question

I would like to know how to define custom sorting criteria for reminders.

For instance, I would like to define a sorting criteria that does the following:

1. Sorts reminders whose due date falls within the next 7 days by day.
2. Assigns equal sorting priority to events within the same week if those events are beyond 7 days from today.
3. Assigns equal sorting priority to events within the same month if those events are beyond 1 month from the current day.

How can I do this (if it can be done at all)?

An answer that provides a general indication of how to define custom sorting criteria would also be sufficient.