I can’t understand why Apple has not included week numbers in iCal. Not even as an option. Well, luckily I found a php script that generates a calendar that you can import into iCal and that way get week numbers as “whole day” events. Ugly? A bit, but it might be worth it.
I made some own modifications to the script. My version accepts 0-2 parameters denoting starting year and ending year (if specified). If neither parameter is specified, the generated calendar defaults to the current year. If only starting year is specified, the script generates the week numbers for only that year.
The script can be viewed and downloaded here. Save the file to your computer and rename it to generate_ical_week_numbers.php. Note that you need php to be able to run the script.
$> php generate_ical_week_numbers.php [startyear] [endyear] > week_numbers.ics
Then import the file week_numbers.ics file into iCal as a new calendar. That’s it.
The original script was found here.