I just kinda scanned through this and saw people posting lots of different versions of this. I think this may be patched. It worked for some people and didnt work for others so it probably doesnt have a high % of success. Heres a fairly detailed version of it:
10 hour dupe:
what you need - a way to anti idle (zoids or cerbs) & being able to run 2 d2 windows at once will be very handy.
make a private game and just leave your character. dont move him or ANYTHING. Anything that you do will cause the time to start over. Use either Zoids or Cerbs anti idle and leave it for at least 10 hours.
after 10 hours in the game blizzard will lose track of your character. from here you will want a friend to make a game or if your doing this by yourself, open a second d2 and create another game with any character EXCEPT the one which is currently idling in the game.
Wait in the new game with your second character for 5min+ to perm the game. Once its permed, leave the game and log on with the same char that has been sitting in its own game for 10+ hours.
We are hoping that bnet did lose track of that char and you will beable to join another game. If you can join another game while still idling in a different game with your other d2 then your golden. Drop all your items off the character that WASNT waiting for 10+ hours in the game that you already permed. leave the game and rejoin with a mule or a different char and your done. just go back to the idling char and try to move him/her somewhere and you will get C/I and probably R/D.