I have some good MH3 and MH4 saves on their respective retail carts; can those saves be transferred to GW for use with dumped roms? How if yes?
Okay this is easier:
1) launch the gateway menu NOT GATEWAY MODE
2) find backup save game (or similar)
3) choose this option. When complete shut down you ds and take out the consoles SD card.
4) you should see a file that says ####.sav (the #'s represent letters, like if it was mario kart it would be AMKE.sav)
5) on the sd card you should also see the gateway saves, for this to work you already need to have a save for the game you want to put on gateway, on the gateway, as in make a character, save, close the game. Anyway, move all those saves to a computer.
6) move the saves back one at a time, every time starting up the game that you want to transfer the save for.
7) when the save reappears in the game, you found the right one, move that save back to the computer in a different location, it should the last of the saves you moved to the sd card.
8) move the saves you have yet to transfer back to the sd card back to the sd card.
9) now the game save you saved to your computer has a name of almost random seeming characters. I think this is the games ID, but I'm not sure. Anyway, copy the name, you don't need the .sav. Now locate the ####.sav clear the name and replace it with the name on your clipboard (the one with the random letters from the other .sav file). So now it should have the same name as the other save you had.
10) move your new .sav file back to the sd card of your console. Boot into gateway mode, open the game. If you followed these steps right then you should have your retail cart save file on your gateway.