Firmware customisation

[Gwegz320]

Hello everyone,
excuse me in advance if this topics is not necessari, but i'm trying to find how to customize my first picture screen on my navigation system when i open the door of my car.

I have installed gdk environement, i have downlaoded NavTweaker, i have a Iso editor (MagicIso) and I have a clean iso file, the last available V32!!!

I dont find where is the navboot file that speak people. Fil who i have to copy on the desktop, and then open in navtweaker to replace the image...

Where is the navboot fil in the system tree of the iso? In the V32 iso i have folder named Mk2/Mk3 and so much more, but nothing about the MkIV like mine...

Can somebody help me please...?

Thanks in advance

PS : After all, on another forum somebody tell me the fil is here : <drive>:\V_2\RR\0101\BMWC01S\app_sw

okey i have open it in NavTweak and located the logon scrren in the roombitmaps section in images.
But I have already the V32 installed, so how to do? I need one older firmware version to downgrade to, and then push in the V32 modded i think? Is it right? If it is, can somebody give me a link to downlaod one older version please? because all the link on the fourm is dead?