I have quite a few events in my Google Calendar and they are all set to Default privacy.

My Google Calendar sharing preferences is currently set to "Show free/busy only":

Picture 2.png http://img834.imageshack.us/img834/1782/picture2ar.png

But I would like to change this to "see all event details"

Picture 1.png http://img864.imageshack.us/img864/7130/picture1tv.png

And change all of the exiting events from "Default" privacy to "Private" - so that all new events I create will be public - but existing events are private.

Picture.png http://img52.imageshack.us/img52/3655/picturevy.png

How can I change the privacy setting for all existing events to Private without having to change them one at a time? I have looked at the Google Calendar webpage and also in iCal and have not found an option in either, and actually in iCal I don't think there are any privacy settings that show up at all.