[gentoo-dev] Patching vanilla-sources with genpatches in catalyst

For my sparc64 port, i need a livecd with kernel 4.8-rc6 that is patched 
to work on a livecd. I'm not going to expect gentoo-sources to be 
released for this kernel, and hacking up the kernel eclass for 4.8-rc6 
doesn't seem like the right way to go. So i was looking for some input 
on the best way to do this.

The first thing that comes to mind is to make a vanilla-sources ebuild 
for 4.8-rc6 and use that in the spec file. Then after doing a 
livecd-stage1 put the genpatches in /etc/portage/patches/... and let the 
epatch_user interface take care of the rest.

Does anyone have any better ideas?