I had the hardest time installing nvidia drivers on my custom kernel. I ended up getting them installed using module assistant.
#apt-get install module-assistant nvidia-kernel-common
When that completes, run:
#m-a auto-install nvidia
Next you need to install the nvidia user space libraries:
#apt-get -t testing install nvidia-glx (change testing to stable or unstable depending upon your distro)
If it asks whether you want to install the thread-local storage libraries, say yes. Next, reconfigure your video:
When it asks for a driver, choose nv. When asked to select xserver modules, select glx and deselct GLCore and dri. Now add the drivers to the appropriate group:
#addgroup --system video
#adduser $user video (Change $user to the user name of the user you want to use the drivers)
#adduser root video
The final task is to make sure the drivers are inserted into the kernel at boot:
#grep -q ^nvidia /etc/modules || echo nvidia >> /etc/modules
If this all works, when you reboot you should see the nvidia splash screen when you reboot. I hope this helps.