Thank you guys for the replies
Let me tell why i want this : for example i want to install cssu thumb
I want to make a clean install so i flash the latest maemo firmware , then i remove all the apps that i dont want to clean some rootfs space , than i install the cssu thumb , and this procedure take me hours to do it
If we have access to firmware modification we cane make a cssu flashing firmware once and all this hard work is done for 5 minutes

There is another chance that we can do this with backupmenu and i tried installing backupmenu , i made a backup of my rootfs and optfs and before the restore i had 98 MB of free rootfs space , after the restore i had 85 MB free , so i dont think its convenient to restore with it