only if you can download safestrap 3.72 made for at and t. you will have only the access to one slot, the main. this means its only allowed to use the stock slot as your system rom i can go into detail I recommend you Google hyperdrive 17.1 xda developers
You have to use Safestrap 3.72 on NC5 as already stated. You can't flash AOSP roms either. It has tobe touchwiz based. Sorry. You'll brick your phone if you try to do anything else and have to restore using odin.