Just want to make sure I understand this - I only get this deal IF I book through a TA, i.e. not if I book direct with the hotel? (4S newbie here - apologies for the dumb question)
As DavidO said, you have to book through a travel agency that Four Seasons has bestowed their Preferred Partner status to. I know of two (and there are certainly more):
Sterling Brownell
PROTRAVEL
If anyone knows any other agencies, please share. (There were some issues about sharing specific agents in an earlier thread -- I hope it is okay to share agencies.)