This is what I usually do which works for most games except the occasional one that requires hex editing on top of it.
First, extract the save game that you want to transfer. Remember the number.
Then go and run the new game and create a save file on the wii.
Then go and extract the new savegame (just pretty much to create the directory on your SD card) and remember that number also.
Put the SD card in your PC, take all the files out of the first directory that you remembered and paste them into the second directory overwriting all the files
Put the SD card back into your wii and use save game manager to install the the save game to the new game region.
I have done this countless times, like when a japan version of a game came out before an american version (WSR comes to mind) and also to have multiple copies of animal crossing
On all the games that I care for I have never needed to hex edit the save files, but with some you do.
The priiloader hacks wont do shit to help you in this situation.