What should I copy from Ubuntu

Hi,
   Sorry for a semi-cross post between the yaboot list and
Gentoo-ppc-users. I'm hoping to get this worked out today.

   I had trouble a week ago getting a new Gentoo PPC install to boot
on my Mac Mini so for kicks I tried Ubuntu which booted fine. I'd like
to get back to running Gentoo and I'm wondering what information I
should retain from my Ubuntu installation. The new Gentoo install is
back on the Mac Mini and completely up to date, so if I can work out
the booting issue I should be good to go. I have not emerge yaboot as
of yet as I don't want to break Ubuntu until the last moment if
possible.

   To boot do I need anything beyond the info contained in the Ubuntu
yaboot.conf, the hard drive partitioning and fstab to get Gentoo
working? That's should be enough to somehow construct things correctly
in Gentoo, correct?

   Also, the Ubuntu install used an initrd. I presume this is because
their one-size-fits-all approach probably requires drivers to boot a
lot of different machines. Previously when I had this Mac Mini running
Gentoo I didn't use one. I don't need to, correct? (Assuming I can
find and build in the right drivers?) Is there anything about yaboot
vs grub that makes it prefer an initrd? For now I used the Ubuntu
.config for my Gentoo kernel and figured I'd trim it down later after
I get the machine at least booting.

Thanks,
Mark