So, after i dump a game, merge the wud files into one and edit the key file would it be ready to install with wupinstaller?
No, it's a WUD dumper. it created a 23GB WUD file.
if you want to use WUP installer, you need to first extract the WUD with discU "c" to extract only the encrypted content files from it which WUP installer will use.
Is there any tuto available to backup disc games into Wii U formated HDD I mean all steps needed?
not sure if a tutorial is really needed, but you need to use different homebrew.
Disc to WiiU USB HDD is a three steps method:
1. dump: Use wudump to create multiple wud on SD and you need to merge them (use the command line from the first post), and get the disc key
2. extract : then use DiscU with the key.bin wudump created : "DiscU.exe key.bin game.wud c"
3. install : then use Wup installer y mod to install the extracted files to WiiU USB HDD. The ticket to use is the one located in /system/02/ folder.
the "key.bin" generated on step 1 is the one to use on step2. it's the disc key, used to extract the disc.
you don't need to find or fix any "title ticket" used by WUP installer on step 3, because the good title.tik will be extracted from step 2 if you use DiscU 4.1b
if you use DiscU 2.1b or an old VGMtoolbox (assuming they fixed it on new version) then you will have to fix the ticket located in /02/ folder before using it with WUP installer.