In order to access any Google services via a client, you will need your Google Sync Code, which can be found in the Search & Help tab of the MyTC portal. If you have any other clients configured, resetting your Google Sync Code will break the connection to those clients until you input the newly reset code.
Inside the Preferences menu, choose the "Accounts" tab and click the Add (+) button on the bottom of the Accounts window.
Once you have clicked "Create", your settings will be applied and it will take several minutes to populate your appointments inside of the iCal application. When this has finished, you will have access to all of your calendars within the iCal application.
Calendars other than your default calendar can be accessed by clicking on the "Window" menu in the iCal menu bar options.