hi guys i know this is rather outdated, but i've managed to create multiple accounts on ical (10.6.2) with 1 gmail login for multiple calendars.
1. Goto Preferences > Accounts
2. Click on +
<ADD AN ACCOUNT>
3. Select CalDAV,
fill in username and password.
Server address - "https://www.google.com/"
4. **IMPT PART! Hold ALT key to change 'create' button to 'continue', forcing manual options
<CALENDAR SERVER OPTIONS>
5. Account Template: None
Username : [USERNAME]@gmail.com
Password :
Server Address:
https://www.google.com/
Server path: /calendar/dav/[CALENDAR ID]/user/, where [CALENDAR ID] is the ical version of Calendar Address available on the Google Calendar webbie > Settings > [CALENDAR OF CHOICE]
Port : [BLANK]
USE SSL : YES
USE KERBEROS: NO
6. Create!
Kudos to all those who've gone before us on this quest for multiple google calendars on ical.
Happy New Year!