By the way, my resolution is detected properly right away. I just go in the nVidia X Server Settings and I can use TwinView without rebooting.
Here's my new xorg.conf (using the ACPI edid) :
VendorName "NVIDIA Corporation"
Option "ConnectedMonitor" "DFP-0,DFP-1,CRT"
Option "CustomEDID" "DFP-0:/proc/acpi/video/NGFX/LCD/EDID"
Has anyone found a solution about the alt+fn keys ?