Sorry! Probably I am not strong in Roman numerals
You device is so brutal as it is old No mass storage mode is supported with it. Only one way to use internal flash memory take place -

1. This topic about automobile analog of your device in particular:
[Only registered and activated users can see links. ]
2. It is advanced manual for all old device without mass storage mode including your GPS:
[Only registered and activated users can see links. ]

All of this is not trivial task but it works!