I was just discussing that exact topic in another thread yesterday. Check this and you should have a good grasp on how to do it. You'll need NUSPacker and the Wii U common key, both easy to find.and how to convert loadiine games to WUP Installer that are not in the Wii U USB Helper? for example Just Dance Wii U insn't in the database so can't be downloaded making JNUS useless.
I only got the loadiine format for that game (Meta, code, content).