Hi,

the pre-compiled kernel (which the cd boots from) is placed in
the /boot-directory of the cd, I believe.

You can copy it from there to your mounted gentoo-partition.

Maybe you also should copy the initrd/initramdisk from this directory
and the /lib/modules-dir.

And of course, you need to add it to yaboot manually.

But I've to say, this kernel is pretty generic, and won't fit your
hardware in an optimal way.

I only used it as a fallback-option once, when I remote-set up a  
headless
system and it worked so far, but better build your own kernel.

Regards,
Friedrich