Check that your /etc/make.conf contains the following:

VIDEO_CARDS="intel"
    INPUT_DEVICES="keyboard mouse evdev synaptics"
    

Especially the "evdev" entry in INPUT_DEVICES is very important. Without it, you will have no working mouse and keyboard, when starting your graphical system. After these changes, make sure that all your X related stuff is compiled with the right options.

# emerge --newuse --deep --update world

You should have DBUS up and running:

# emerge dbus
# rc-update add dbus default
# /etc/init.d/dbus start

Nowadays' X servers usually rely on the hal daemon. You should emerge and start it:

# emerge hal
# rc-update add hald default
# /etc/init.d/hald start

If you haven't done so already, it is time now to install your server. You can either emerge gnome for a complete desktop environment (or emerge kde if you can't help it), or emerge xorg-server for the bare server. Make sure that you have read the pre-flight checklist, before you start X for the first time.

You should now create a skeleton X11 configuration file . You can either take /etc/X11/xorg.conf.example a try, or let it generate:

# emerge --oneshot mkfx86config
# mkfx86config.sh

Under normal circumstances, a startx or /etc/init.x/xdm start should now bring you into a basically working graphical environment.