I've called KLM to put my desired itinerary on hold. That worked just fine, and I have the hold through Friday night.

Now, I'm going to try to call Delta, have them struggle with booking me on the KLM SFO->AMS, then ask them to call KLM and try to take over my reservation using the reservation reference number that KLM gave me.

I will be kind of shocked if this works, but it's probably worth a shot. Any thoughts or tips?