If you’re wondering how to create a chroot environment in the first place while reading my previous post, then this post is for you.

Gentoo:

• Download gentoo stage 3 installer

wget http://mirror.gentoo.gr.jp/releases/x86/2006.1/stages/stage3-i686-2006.1.tar.bz2

• Create a chroot folder

mkdir chroot-gentoo

• Extract it

sudo tar xvjf stage3-i686-2006.1.tar.bz2 -C chroot-gentoo

• Mount proc and dev

sudo mount -o bind /dev chroot-gentoo/dev
sudo mount -o bind /proc chroot-gentoo/proc

• And possibly some other directories too

sudo mount -bind /usr/portage chroot-gentoo/usr/portage

• And that’s it, you can start chrooting now

sudo chroot chroot-gentoo /bin/bash

• You might want to install some essential packages

emerge --sync
emerge vim 
Exit when you're done
exit
Dont forget to unmount what you have mounted
sudo umount chroot-gentoo/dev chroot-gentoo/proc chroot-gentoo/usr/portage

You can have a debian chroot system too

• Install essential package

as root

echo "dev-util/debootstrap ~x86" >> /etc/portage/package.keywords
emerge debootstrap 

• Populate your chroot folder using debootstrap

debootstrap sid chroot-debian http://mirror.pacific.net.au/debian/

• Mount proc and dev

sudo mount -o bind /dev chroot-debian/dev
sudo mount -o bind /proc chroot-debian/proc

• Start chrooting now

sudo chroot chroot-debian /bin/bash

• Install your favorite packages

apt-get update
apt-get install <list your package here>

• Exit once done playing with the chroot environment
  

exit

• Clean up some mess

sudo umount chroot-debian/dev chroot-debian/proc

Just do whatever you wish with your chroot environment, and you can just delete the chroot folder when you realized that you messed up too much already.