UTF-8

First set the language variables in your /etc/make.conf, so that programms like KDE, Firefox or OpenOffice.org also install their language packs:

File: /etc/make.conf

LINGUAS="de"
LANGUAGE="de"

This is the default installed by OpenRC, but ensure it's set:

File: /etc/rc.conf

unicode="YES"

Now edit /etc/locale.gen so that your glibc generates the right locale:

File: /etc/locale.gen

de_DE.UTF-8 UTF-8

and run

# locale-gen

afterwards.

Then we need to create a new file to set some system-wide environment variables:

File: /etc/env.d/02locale

LANG="de_DE.utf8"
LC_ALL="de_DE.utf8"

and activate it via

# env-update

Now change your keyboard layout:

File: /etc/conf.d/keymaps

keymap="de-latin1"

And last but not least your console font:

File: /etc/conf.d/consolefont

consolefont="lat0-16"