How to update my *main* Google calendar with free/busy info from Zimbra?

[MAdMoNKEY]

Can someone help me solve this issue (or let me know this isn't possible yet, so I can stop looking/hoping/yearning)?

• My company uses Google Apps.
• Everyone looks at each other's *main* Google Calendar to determine free/busy times for meetings.
• I use Zimbra because Zimbra is a much better fit for my needs.
• I need a way to export my free/busy information (from multiple Zimbra calendars) to my *main* Google calendar.
• I prefer this to be a 1-way sync - i.e. I don't think I can sustain a process of exporting my Zimbra data each day and importing it manually into my Google Calendar.

Can anyone offer me some insight? I went through all the options I could think of in my Google Calendar, but I don't see any way of getting this data into my main calendar (I think I can create a new Google Calendar and have it import this data, but unfortunately people at my company are trained to only check the main calendar).

Thanks for the help!

P.S. I know there are lots of posts/questions about bi-directional sync with Google calendars, etc. I tried searching for my answer but I haven't found anything that speaks to my situation, hence my post.