Ok so you have two options.
You can wait for your friend to get you his copy of OoT and hopefully it either already has the GW save on it or you have a way to import the gw save file.
Or you can follow the first few parts of
this guide to get to a point where you can boot the GW menu.
You will need to follow sections I and II, and I personally recommend using Method 2 in section I since it is much easier. Once you finish section II, you will have a nand.bin back up and an emunand partition on the sd card and you can continue from page 44 with step 8 "Unlink sysNAND and emuNAND". Keep in mind that since you have a N3DS you cannot easily eject your sd card so I highly suggest you do not put the sd card back in until after the format completes (you would have removed it during Section II of te guide I linked so you could restore your content after setting up the emunand partition.