Here's how to configure the Apple Mail client to use the Application Specific Password. (I'll leave it up to you to check out Google's site on how to obtain the ASP.
You need to configure both Incoming and Outoing mail.
CONFIGURING INCOMING MAIL
With the Apple Mail client open, go to Preferences >> Accounts. You can access Preferences by holding down the Command key and tapping the "," (comma) key.
You will enter the 16 digit (currently) password in the "Password" field. Save your changes when you are prompted.
CONFIGURING OUTGOING MAIL
Open the "Outgoing Mail Server window by clicking the drop-down arrow at the right of the window.
Select "Edit SMTP Server List..."
CONFIGURING YOUR iPHONE
- Open up "Settings"
- Scroll down to "Mail, Contacts, Calendars"
- Select the account you need to configure
- Open the specific account settings
- Enter in the Application Specific Password in the "Password" field.
Once you have entered the password, the iPhone will go out and authenticate with Google. You'll see a series of green check marks that indicate you've correctly configured the account. If you do not see those check marks, try re-entering the password. It's easy to mistype a 16 digit password.
Open iCal/Calendar preferences (Command + ",") - select your account (if you have more than one) - then follow the steps illustrated below.