It happened! The pentoo installer is finally here!
Jensp did an awesome work and ported the Arch linux installer to pentoo.
It is still in testing for now, but you are welcome to try it, I just did and can tell it's easy as pie.
The following is done from a booted pentoo-2009.0 livecd with the network already configured
First, sync your pentoo repo.
layman -s pentoo
Unmask the pentoo-installer
echo "=pentoo/pentoo-installer-0.1.3" >> /etc/portage/package.keywords/pentoo
Emerge the installer
Just run it and follow the informations given by the menus
Let us know what you think and if you encounter a bug, please report it on the trac development site.
Update: pentoo-installer has been stabilized, you don't need to unmask it