Hiya, I have been looking everywhere for this hack and after months of looking here it is :o)
1. without disk, press 0 (4-5 times)
2. press REPEAT
3. Press 3 8 7 6 7 (you will see a 2 flash up on the top left, 2=region2)
4. Press 9 (you should see 9 flash up in the top left)
5. Press OPEN then CLOSE
and that should be multi region, work for me.
Lee