The Gentoo desktop install is a good documentation about this installation.
You might as well pre-fetch the installation files
with a emerge -f ... or a wget ...
Install XFree:
emerge xfree
env-update && source /etc/profile
For an Epia-M board, copy the Via drivers into the system:
cd /
wget <...>/via-xfree.tar
tar -xvf via-xfree.tar
rm via-xfree.tar
If you can't find a /etc/X11/XF86Config configuration file on a server,
configure screen, keyboard and mouse:
/usr/X11R6/bin/xf86config
If you forgot to specify the keyboard layout,
insert a line in /etc/X11/XF86Config such as:
Option "XkbLayout" "fr_CH"
Choose to use the X font server:
/etc/init.d/xfs start
rc-update add xfs default
Start an X session
startx