Heres is how i do:
1- Get the original iso from kallstar (any)
2- Get the main.dol from .iso (using Wiiscruber)
3- Using an hexdecimal program i change (find and replace) the ID of the game to the new ID (ShowMiiWads to know it)
4- Put main.dol back to the iso
5- get the forwarder GAMEID.DOL...