I already got it working and posted the spec and Makefile patch here.
(I've also got my stuff for building from git branches working now.)
Nobody answered about whether they wanted it committed.
I didn't do it in a way intended to produce different variant rpms called
kernel-vanilla-V-R, if that's what you had in mind. That requires
basically duplicating all the innards of the spec file. I don't think that
should be attempted without a complete cleanup of the spec file to become
What I've done is sufficient for making a vanilla build like this one: