Well I just read where some folks use Calculate Linux Scratch 
to install gentoo. I guess you use the Calculate installer 
and then just easily  convert to gentoo as part of a new installation.
You can even customize your install .
"Later on, you should only have to remove sys-apps/calculate*, switch
profiles, and rebuild @system and @world. " I think you also have
to point to a gentoo mirror too.
I'd be curious to hear about anyone using Calculate Linux for there
installation. I'd be most curious about raid-1 (mirroring) stories
with btrfs and calculate linux...