Mine

mkdir /mnt/gentoo
mount /dev/sda3 /mnt/gentoo/
mount /dev/sda1 /mnt/gentoo/boot/
mount /dev/sdb2 /mnt/gentoo/home/
mount /dev/md0 /mnt/gentoo/var/
chroot /mnt/gentoo/ /bin/bash

export TERM=xterm
source /etc/profile 
env-update