The best way to do this is to probably first write a script or windows program to install the nvidia driver using the .inf file that comes with the hardware. Probably using the UpdateDriverForPlugAndPlayDevices(...) function: http://msdn.microsoft.com/en-us/library/ms792968.aspx
Use this this executable and the needed driver files to create your own custom component in the component designer. Set the executable to run during the FBA and add this component to your .slx file