This afternoon I was trying to setup my work calendars from gmail in ical. The problem I kept running into was that I wanted to see my coworkers calendars, but didn't want to go to calendars.google.com everytime. These are some instructions for how I got it to work for me (I'm assuming that you've already setup your google calendar to sync with ical via CalDAV):

  1. Open up preferences, click on the account in question step 1
  2. Click on delegation step 2
  3. Check all the boxes of co-worker calendars you want to see. step 3