First install Xorg. You should have compiled your kernel and the nvidia module keeping in mind the need to run Xorg.

http://www.gentoo.org/doc/en/xorg-config.xml

emacs /etc/make.conf

Changes to make.conf:

VIDEO_CARDS="nvidia"

[/code]

emerge -pv xorg-drivers

emerge xorg-server

env-update

source /etc/profile
Finally try a startx

If you momentarily get a blank screen, X may be setup correctly. Can test with emerge twm (but remeber to unmerge them)
emerge -av kde-meta
If there are use changed you need to write:
emerge -av kde-meta --autounmask-write
(Watch for another command which writes merges the changes to config files)
After installing and compiling packages of KDE, we can try to start kdm
kdm[/code]

If all went well, KDE should start. I got a few errors with dbus and consolekit, which caused KDM to show windows without the resize/min/max buttons, and a few error message popups.
Consolekit session failed to connect to socket.
Solved by:

First see if dbus starts fine:

/etc/init.d/dbus restart
If it does, then:

rc-update add dbus default

rc-update add consolekit default
To make KDM start automatically at boot:

sudo emacs /etc/rc.conf
Add the line:

DISPLAYMANAGER="kdm"
Then add xdm to default runlevel:
rc-update add xdm default
Joel G Mathew
Joel G Mathew, known in tech circles by the pseudonym Droidzone, is an opensource and programming enthusiast.
He is a full stack developer, whose favorite languages are currently Python and Vue.js. He is also fluent in Javascript, Flutter/Dart, Perl, PHP, SQL, C and bash shell scripting. He loves Linux, and can often be found tinkering with linux kernel code, and source code for GNU applications. He used to be an active developer on XDA forums, and his tinkered ROMS used to be very popular in the early 2000s.
His favorite pastime is grappling with GNU compilers, discovering newer Linux secrets, writing scripts, hacking roms, and programs (nothing illegal), reading, blogging. and testing out the latest gadgets.
When away from the tech world, Dr Joel G. Mathew is a practising ENT Surgeon, busy with surgeries and clinical practise.