The Pilar Yacht Club stopped running Box shuttles this year. Your best bet is to find a Pilar local at the cafe and ask them if they will run it for you. You will need to drive them up there and pay them about $40-60 depending on your negotiation skills.
Another option is to call around the outfitters and see if they have a hungry raft guide that doesn't have a boat for the day. And your final option is to hang out at Taos Junction Bridge (LTB Take Out) first thing in the morning and hope you can hook-up with another boater looking to do the same.