Did you try these steps (posted earlier in this same thread):
1. In IE10, click on the Tools button (Alt+T)
2. Click on F12 developer tools
3. In the window that pops-up, click on Tools
4. Expand the "Change user agent string" tab and select "Apple Safari (iPAD)"
5. Go back to the IE10 window and go to this URL:
https://m.google.com/sync/settings/
6. Sign into your google account if you aren't, already.
7. Click on "WindowsPhone"
8. In the URL, if you see this string (without the quotes): "supportMultiCalendars=false", change this to "supportMultiCalendars=true" and reload the page.
9. Now your google calendars will show up. The main google calendar will show up as "My Calendars". The other calendars will show up as "Shared Calendars" and calendars under this option will not be selected.
10. If you cannot select these "other calendars", disable JavaScript in IE10. Do this by following instructions here (these instructions are for IE9, but apply to IE10 also):
http://browsers.about.com/od/interne...script-ie9.htm
11. Select the calendars you want to add.
12. Click on "Save".
13. On your WP8 device, go to settings -> email+accounts and sync your Google account.
14. Open the Calendar app on your WP8 device to make sure your "other Google calendars" now show up in the app.
And yes, don't forget to re-enable JavaScript, if you had to disable it in step 10 above.
I believe somebody confirmed that these steps worked. Hope this helps!