Install sys-apps/n8x0-env with USE='X' from n8x0 overlay.
Run rc-update add nokia-tablets-pointercal default.
Uncomment following line in /etc/ts.conf:
module_raw input
Create /etc/X11/xorg.conf with following contents.
Section "Monitor"
Identifier "monitor"
EndSection
Section "Device"
Identifier "device"
Driver "omapfb"
Option "fb" "/dev/fb0"
EndSection
Section "Screen"
Identifier "screen"
Device "device"
Monitor "monitor"
EndSection
Section "InputDevice"
Identifier "touchpad"
Driver "tslib"
Option "Device" "/dev/input/event3"
Option "EmulateRightButton" "1"
Option "CorePointer" "true"
EndSection
Section "InputDevice"
Identifier "keypad"
Driver "evdev"
Option "Device" "/dev/input/event2"
Option "CoreKeyboard" "true"
EndSection
Section "InputDevice"
Identifier "pwrbutton"
Driver "evdev"
Option "Device" "/dev/input/event0"
EndSection
Section "ServerLayout"
Identifier "layout"
Screen "screen"
InputDevice "touchpad"
InputDevice "keypad"
InputDevice "pwrbutton"
EndSection
Section "ServerFlags"
Option "AutoAddDevices" "False"
EndSection
If you're using xf86-video-fbdev instead of xf86-video-omapfb,, replace Device section with following:
Section "Device"
Identifier "device"
Driver "fbdev"
EndSection
Install any desktop environment (lxde-meta/kde-meta/gnome/whatever).
Create user for yourself and set password.
Configure /etc/conf.d/xdm.
Run rc-update add xdm default and reboot into Gentoo. If you did everything right, you'll see xdm welcome screen.
N800 doesn't have keyboard, so if you chose xdm method (without autologin), you won't be able to enter login/password.
Configure XSESSION variable in /etc/rc.conf.
Add following command to local_start function in /etc/conf.d/local so X starts on boot
su - <user_login> -l -c startx &
Reboot into Gentoo and you should see X desktop.
For GTK-based environment install app-accessibility/florence from n8x0 overlay.