First, you'll need to obtain an application-specific password for alps from the app passwords page on your Google account.
Start alps with these upstream URLs:
alps imaps://imap.gmail.com smtps://smtp.gmail.com \ carddavs://www.googleapis.com/carddav/v1/principals/YOUREMAIL/ \ caldavs://www.google.com/calendar/dav
YOUREMAIL with your Google account's e-mail address.
Once alps is started, you can login with your e-mail address and the app password.