well in some days i'll post a full tutorial but here a trick for you to use:
Find a rom (google for it,i've done it only on a i9000b rom) that have an recovery mode recognized by adb and HAVE ROOT.
***search on google for 'fdisk' commands first***
You MUST*¹ remake your partition table manually,so the phone have the /data partition back to boot.
YOU SDCARD MUST HAVE THE FOLLOWING PARTITION TO BOOT ON AND RECOGNIZE INTERNAL SDCARD:
run adb shell
p (you should see your partition table,POST HERE BEFORE CONTINUING)
YOU ARE NOW ABOUT TO REMAKE YOUR PARTITIONS:
partition 1 will correspond to mmcblk0p1(SDcard) and partition 2 will correspond to mmcblk0p2 (DATA)
**DO ONLY AS I SAY HERE, UNLESS YOU MAY GOT I/O ERROR ON YOUR SDCARD AND ITS ALL OVER. I say because it happened to me and i had to dissolder the internal sdcard an use only the external.**
**********IF YOU DONT HAVE ANY IDEA OF LINUX COMANDS: DO NOT PROCEED !!!!!!!!!*************
tap on adb:
n (will create a new partition)
1 (partition number)
press enter on keyboard so it selects the first block
get a calculator and estimate the size of the partition 1.IT MUST HAVE around 2GB left.
write the block number you got in calculator(BE SURE OF WHAT YOU TAPE HERE)
b (partition 1 is done and formatted as fat 32)
enter on keyboard
enter again so it select the last block
(DO NOT TYPE COMMAND "T" FOR PARTITION 2, IT BY DEFAULT SET TO LINUX EXT FORMAT)
p (you will see you new partition table)
****IT MUST HAVE 2 partitions, partition 1 is in fat 32 format and partition 2 is in linux format(AND MUST HAVE AROUND 2GB)****
w (IT WILL WRITE YOU NEW PARTITION TABLE ON YOU SDCARD,SO BE SURE IT's ALL CORRECT)
p (you should see your new partition table, if ok reboot your phone, flash an stock rom for vibrant,root it,backup it,and enjoy.)
In some cases you can use gparted to do this, without doing it manually,
you shoud only mount mmcblk0 before.
you can run this command line on adb shell to mount it:
echo /dev/block/mmcblk0 > /sys/devices/platform/s3c-usbgadget/gadget/lun1/file
I'll connect on XDA again tomorrow at about 3:00 pm in Brazil (-3:00GMT)
***In any doubts ask for me in this post (NOT PM) and wait for me or any developer that knows about it to help you.