Sorry, guys. I thought I could beat the system by trying to upload the Nikon D2X Picture Control onto the Nikon D90 but in my review, the custom picture control file extension created by Nikon D90 has a different extension file *.NCP while the one downloaded from the Nikon web site of Nikon D2X has a *.NOP file extension!
Nevertheless, when attempting to load those files, the Nikon D90 could not detect those 3 custom picture control files meant for the Nikon D300.
But again, some affirms that those custom picture control files are redundant as
D2X mode I is the same as Portrait
D2X mode II is the same as Neutral
D2X mode III is the same as Vivid
O well, at least now we know!