It looks like there's a new folder where the pngs are stored as well..
Here's what I did
SSH into iPhone
Make backups of existing files by.. (keep the quotes to handle the spaces)
Code:
cd "/System/Library/Carrier Bundles/ATT_US.bundle"
cp Default_CARRIER_ATT.png Default_CARRIER_ATT.png.orig
cp FSO_CARRIER_ATT.png FSO_CARRIER_ATT.png.orig
cd "/private/var/mobile/Library/Carrier Bundles/ATT_US.bundle"
cp Default_CARRIER_ATT.png Default_CARRIER_ATT.png.orig
cp FSO_CARRIER_ATT.png FSO_CARRIER_ATT.png.orig
Now upload your custom png files to:
"/System/Library/Carrier Bundles/ATT_US.bundle"
AND
"/private/var/mobile/Library/Carrier Bundles/ATT_US.bundle"
Remember, the files MUST have the same name as the existing .png files
STOP HERE, RESPRING
If you ever want to restore the original carrier logos..
Code:
cd "/System/Library/Carrier Bundles/ATT_US.bundle"
cp Default_CARRIER_ATT.png.orig Default_CARRIER_ATT.png
cp FSO_CARRIER_ATT.png.orig FSO_CARRIER_ATT.png
cd "/private/var/mobile/Library/Carrier Bundles/ATT_US.bundle"
cp Default_CARRIER_ATT.png.orig Default_CARRIER_ATT.png
cp FSO_CARRIER_ATT.png.orig FSO_CARRIER_ATT.png