Same as you do with SDCafiine, build with Sm4shExplorer, it'll make the patch folder, just add it to SD:/wiiu/games/Smash Bros. [AXYE01]/updates/v208/content/patch and just replace the existing files (v208 or whatever the latest is, you could also make another folder, copy it, and name it to whatever mod you're testing to keep the original update clean, it'll still detect the name even if it's some weird name, have "4.1.0" for MK8)