The basics are the same for all modern Garmin devices. Follow the tut in initial post here as a guide and be sure that the replacement images you use are the same specs as are originally in the nuvicam logo. But firstly you need to 'dump' region 16 from your device to obtain the logo bin file, then replace the images and reflash the modded bin file back to region 16. If you don't understand what to do best not attempt it. We can guide you but the risk is yours. Seems you do need a 'step-by-step', but ONLY attempt this after doing some more reading on how it's done. Look at [Only registered and activated users can see links. ] of [Only registered and activated users can see links. ] for the SD basics. HEED THE WARNINGS. You'll need to modify the Update.txt file:
Spoiler:
Presently it reads this in the folder 'NV rgn16 dump&write Template - to 2':

rrgn,16,2:/16_backup.bin
xrgn,16,2:/16.bin
reboot

That's to both dump and write to region 16. Firstly you will need to dump the region separately, then change the image/s in the bin file and write it back separately. So your first action is to do this:

rrgn,16,2:/16_backup.bin
reboot

That will give you the bin to modify. After you have done that, save it as '16.bin' and place it as detailed in P#91, then run this to write it to region 16:

xrgn,16,2:/16.bin
reboot


Remember to save a copy of your original bin file in case something goes wrong or you want to write it back.