First make sure you have a kernel downloaded same as the build you are running on now.
Should be under /usr/src/linux
# eselect kernel list
# eselect kernel set 3
where 3 is the one your system is build on , you get the idea.
Also provided eselect is installed " gentoolkit " if I remember correctly.
Okay download them from this link and then save to say /home/me/Desktop.ftp://download.nvidia.com/XFree86/ftp://download.nvidia.com/XFree86/Linux-x86/
Next exit / logout of kde / gnome / xfce gui anything you might be using.
Then as root cd to say /home/me/Desktop
To install use:
# sh ./NVI*.run
and follow the prompts even if errors = yes and continue and let the config tool of nvidia do it''s thing.
then restart and ot should work or before restart edit /boot/grub/grub.conf and add " xdriver=nvidia res=1440x900" or the res your screen should default to same as with cheat codes at startup of live cd = same result and then reboot.
Now you should eventually see the nvidia page and then say KDE / Gnome / gui of your choice you have installed.
Hope this helps.