I believe its in the
...if using a separate USB drive for shared storage
or
/opt/piratebox/share/Shared/content/img
/opt/piratebox/share/Shared/content/locals
if using the spare space directly on the SD card.
(requires linux, maybe OSX to access. Windows does not have native support for ext file systems.)
content/imgfor images
content/localsfor text
...if using a separate USB drive for shared storage
or
/opt/piratebox/share/Shared/content/img
/opt/piratebox/share/Shared/content/locals
if using the spare space directly on the SD card.
(requires linux, maybe OSX to access. Windows does not have native support for ext file systems.)