The link supplied by Cobbydaler looks straight forward enough dragon.
Install proprietry Nvidia drivers (a choice that is up to you), Debian also have a wiki entry here:
http://wiki.debian.org/NvidiaGraphicsDrivers
Which may help - open or closed source drivers are up to you.
The steps after that are just adding the compiz-fusion repository to your sources.list ;backup your original sources.list with:
sudo cp /etc/apt/sources.list /etc/apt/sources.list.old
or something similar (I'm using Kubuntu as the base - ensure sources.list is in the same path)
Of course with any repository - you need to trust what they are supplying you - have a Google around to confirm you are happy the source is trusted.
I don't use Nvidia cards - so have no particular experience, but it seems fairly straight-forward.
Best of luck
Incidentally the kernel you have created used Debians kernel tools - which 'changed' the vanilla kernel to work on Debian - so in essence the kernel is no longer vanilla - but a mute point really
EDIT:
If the .deb for compiz has been packaged correctly - all dependencies should be sorted out by apt (fingers crossed)