Maybe you could take my kelftool, decrypt it, and re-encrypt the generated ELF as fmcb or dnasload KELF...
This is exactly what I did to make it work. I tried many times to install dvd updates via kelfbinder, sometimes i got an error red screen, changing procedure i noticed that the update was installed (maybe only renaming or reencrypting the elf, i don't remember) however even copying attached files to the right folder the dvd fails to start and i got back to osd in a loop. Then I understood that the starting elf was encypted so I thought that decrypting an reencypting in dnasload mode would work and that way it definitely works, the dvd starts in rgb mode (not green). Maybe we can talk to krhacken to have a repack or we could do by ourself, maybe we can include also the dvdplayer updates in an archive (remember that many files are redundant such as dvdplayer.elf itself)... At this time we have only this working method (choose package, decrypt, encrypt-dnasload, install via kelfbinder, copy attached files via uLaunchELF), it is enough for me to not use a pendrive and windows command line, to have a console side install method, but in the next months maybe your KelfBinder could become the standard to apply dvdplayer updates including a proper lua script and a folder containing every non redundant file by dvdplayer package by krhacken, and a user friendly selection on kelfbinder side of model/device/version/progressive/region/language. Each memory card dvdplayer.elf needs to be processed via kelftool. However what do we have to do with PS2 USB DVDPlayers and PSX DVDPlayers? Are they also encrypted? Do they need to be processed via kelftool dnasload?