I recently goofed and upgraded my 3DS to the latest firmware forgetting that I hadn't upgraded my DSTWO firmware first. I don't have access to a DS lite aside from buying one so I googled around and stumbled on this: http://forum.supercard.sc/thread-8832-1-1.html
I can confirm the method has worked perfectly for me twice now including the most recent firmware update (6.2.0-12E).
A basic summary of the method:
1. Grab the latest update file from http://eng.supercard.sc/manual/dstwo/download.htm
2. Extract the 'dstwoupdate.dat' file to the root of your SD card.
3. Rename the 'dstwoupdate.dat' file to 'dstwoupdateb.dat' so just add a 'b' on the end.
4. Put your SD card back in your DSTWO, boot up your 3DS and go to play your DSTWO as you normally would.
5. When the screen tells you 'an error has occurred, restart the system etc...' leave your 3DS open and running on this screen for a MINIMUM of 3 minutes (apparently less that this can brick your DSTWO so I left it going for 5 minutes just to be on the safe side).
6. Turn off your 3DS and put your SD card back into your computer.
7. Delete the 'dstwoupdateb.dat file from your SD card.
8. Put the SD card and DSTWO back together and you should be up to date.
Apologies if this has been posted before, I did some searching and couldn't find this method on the temp so figured it might help someone out.
I can confirm the method has worked perfectly for me twice now including the most recent firmware update (6.2.0-12E).
A basic summary of the method:
1. Grab the latest update file from http://eng.supercard.sc/manual/dstwo/download.htm
2. Extract the 'dstwoupdate.dat' file to the root of your SD card.
3. Rename the 'dstwoupdate.dat' file to 'dstwoupdateb.dat' so just add a 'b' on the end.
4. Put your SD card back in your DSTWO, boot up your 3DS and go to play your DSTWO as you normally would.
5. When the screen tells you 'an error has occurred, restart the system etc...' leave your 3DS open and running on this screen for a MINIMUM of 3 minutes (apparently less that this can brick your DSTWO so I left it going for 5 minutes just to be on the safe side).
6. Turn off your 3DS and put your SD card back into your computer.
7. Delete the 'dstwoupdateb.dat file from your SD card.
8. Put the SD card and DSTWO back together and you should be up to date.
Apologies if this has been posted before, I did some searching and couldn't find this method on the temp so figured it might help someone out.