It's been a few yrs since I was involved with Boeing products but I think if you take a close look at the front matter in the FCOM or FCTM you'll find a statement stating something to the effect that the procedures therein are "recommended" and operators may deviate as they see fit. There is no need to notify Boeing. (It's there somewhere)
You will usually need an NTO if you deviate from an AFM procedure though.
In practice I experence this issue regularly and can confirm that the same applies for Airbus, Douglas, De havilland, and Canadair. I have been taken to task on the NTO issue once in a while by regulatory authourities and I usually just dig out the reference stated above to quiet their concerns. Works like a charm.