No need for that at all. Just go into your Google Calendar and then click on the Settings link on the top right of the page. Then click the Calendars link and then the name of the calendar you want to sync. Then at the bottom of that window there will be something that says Private Address click the green iCal button and copy the address that it gives you.
Open iCal go to the Calendar menu and select Subscribe. Copy the address in there and click OK and voila all sorted.
Edit : Obviously you add events with Google client still but it allows you to view the information from you Mac using iCal.