Have successfully made my 122 play multi region using hack posted by mew on Wed. the 13th june, which is basically as you say:-
1. Turn power on ( no disk in drive)
2. Press menu
3. Then press 1, 6, 7, and press mute to get all regions.
4. Press exit.
I carried all this out on my remote.
Hope this helps. Have another go.
Best of luck.