How to Modify *only* the Fullscreen VC frame of a particular title

[staticasaurus]

Hi there. I am trying to modify the Virtual Console fullscreen frame of Pokemon Crystal (the one you get when you press start or select). I'm having some issues.

What I tried:

I have 3DS CFW with Luma. So I used godmode9 to dump the ROM. Then I used Ultimate GBC VC Injector to inject the custom frame into the CIA. I realize that NSUI is recommended over that, but I think both are depreciated? Not sure.

Anyway, now I have a CIA file, but I don't want to just install that file. Firstly, I have a save file I want to retain. And more importantly, Pokemon Crystal VC has patches that come installed with the app that I want to still have access to. So if possible, I'd like to *either* reinject the modified ROM/CIA back into the app. OR just modify the VC fullscreen frame.

Can anyone help me?

 

[staticasaurus]

Updating this thread with a solid path forward for those that come looking after me.

The patches are not applied to the ROM, rather, they are located in the RomFS, and seem to run with the ROM. If dumping the ROM grabs the entire RomFS (I think it should), then the patches went with it.

So rather than tool around with reinstalling my CIA and then backing my up save from the original and injecting it into mine, the general process I'm going to try is:

1. Use godmode9 to dump the Rom of the official Pokemon Crystal VC.
2. Use that ROM in conjunction with NSUI and my custom faceplate PNG to create a new installable CIA.
3. Install the CIA, then use godmode9 to dump the Romfs, and get the (hopefully) updated face_cgb(dot)ttp file. The hope here is that NSUI correctly coded my PNG into the tpp file, which will be found at the bottom of the root directory for the RomFS.
4. Delete the app I created and installed.
5. Use layeredFS to replace the original face_cgb(dot)tpp with the file I got out of the CIA I created.

If all goes well, it should work. I'll update back when I figure out if it worked or not.