Ok here is a way to dump the nb file and then dump its contents.I have already done that, including xip
Use itsutils and following command in dos window :
psdread -1 0 0xDISKSIZE os.nb
Then use imgfs tools or tazio tools to dump, and further processing.
We need now how to flash back the custom os.nb to omnia
still searching for sd card flashing combinations