If you have kdm (for example you are using KDE), then in menu on logon screen you can choose option to exit X server. If you are using gdm (or GNOME), then switch to virtual console by CTRL+ALT+F1, login and invoke command
sudo service gdm stop
then Xorg should stop, and you can install NVIDIA drivers.
I seem to be getting close, but still am missing something and have been unable to install the NVIDIA program.
Please be more specific. Some error messages shown or you can not find application? You should known where is your program downloaded, for example if you downloaded drivers to "/home/someusername/NVIDIA-Linux-x86-304.88.run" then do
sudo chmod +x /home/someusername/NVIDIA-Linux-x86-304.88.run
To go back to desktop, you can invoke
Make sure you have no running important applications and you saved your work, all desktop programs will be terminated when you quit X server.