You need a power saves USB dongle or a old 3ds with 9.2 to install a save to a copy of oot apparently some copies don't work but mine did. Check gateways site and read every thread just to make sure you don't do anything wrong.
Don't believe you understood my question, or I worded it poorly. I don't care about gateway for the time being, I just want to get emuNAND on my system. I wanted to know how I would backup my current sysNAND (if you can even do that) before attempting to put emuNAND on my N3DSXL.