Это не один файл 
Опишу свой способ, но, сразу скажу, он не единственно правильный
Создайте файл /etc/env.d/02locale вида
LC_ALL="ru_RU.UTF-8"
LANG="ru_RU.UTF-8"
Убедитесь, что установлен пакет media-fonts/terminus-font.
Приведите следующие файлы к виду
/etc/conf.d/keymaps
# Use keymap to specify the default console keymap. There is a complete tree
# of keymaps in /usr/share/keymaps to choose from.
keymap="ru"
# Should we first load the 'windowkeys' console keymap? Most x86 users will
# say "yes" here. Note that non-x86 users should leave it as "no".
# Loading this keymap will enable VT switching (like ALT+Left/Right)
# using the special windows keys on the linux console.
windowkeys="YES"
# The maps to load for extended keyboards. Most users will leave this as is.
extended_keymaps=""
#extended_keymaps="backspace keypad euro2"
# Tell dumpkeys(1) to interpret character action codes to be
# from the specified character set.
# This only matters if you set unicode="yes" in /etc/rc.conf.
# For a list of valid sets, run `dumpkeys --help`
dumpkeys_charset=""
# Some fonts map AltGr-E to the currency symbol ¤ instead of the Euro €
# To fix this, set to "yes"
fix_euro="NO
/etc/conf.d/consolefont
# consolefont specifies the default font that you'd like Linux to use on the
# console. You can find a good selection of fonts in /usr/share/consolefonts;
# you shouldn't specify the trailing ".psf.gz", just the font name below.
# To use the default console font, comment out the CONSOLEFONT setting below.
# This setting is used by the /etc/init.d/consolefont script (NOTE: if you do
# not want to use it, run "rc-update del consolefont boot" as root).
#consolefont="default8x16"
consolefont="ter-k16n"
# consoletranslation is the charset map file to use. Leave commented to use
# the default one. Have a look in /usr/share/consoletrans for a selection of
# map files you can use.
#consoletranslation="8859-1_to_uni"
# unicodemap is the unicode map file to use. Leave commented to use the
# default one. Have a look in /usr/share/unimaps for a selection of map files
# you can use.
#unicodemap="iso01"
Добавьте необходимые сервисы в загрузку
rc-update add consolefont boot
rc-update add keymaps boot
Убедитесь, что в файле /etc/locale.gen раскомментированы строки
en_US.UTF-8 UTF-8
ru_RU.UTF-8 UTF-8
...остальные можно закомментировать.
Выполните от root'а
Установите глобально USE-флаг nls.
Убедитесь, что в /etc/make.conf есть строка
Выполните
emerge -puDNv --with-bdeps=y world
Перезагрузитесь или выполните команду
/etc/init.d/consolefont start
/etc/init.d/keymaps start
Был, был и весь вышел...
