That might depend on the tools you have.
Acrobat is not capable of mixed control.
With a printer driven by a RIP you might be able to define mixed media.
Send the whole job as color. Within the Properties tab for the Printer you would define a page range, perhaps 2-54 as gray. A desktop printer is not likely to have this ability.
If the 2 color pages are the first and last (I'm thinking your outside front and outside back covers) you might send pages 3-54 as gray. Than send pages 1-2, 55-56 seperately. (This would be a deal breaker if you needed the printer to print, collate, fold & stitch a finished book. I have steps for that scenerio.)