Go here
http://wiki.gbatemp.net/wiki/List_of_WiiU_homebrew
Grab Saviine
Extract it somewhere
Put the wiiu folder on your sd card
Run the dump.bat on your pc
Boot into Homebrew Launcher
Load Saviine
Use the Dpad to set the ip address displayed in Saviine to the ip address of the pc running the dump.bat/saviine server
Press A or whatever Saviine ask's you to press and it will load saviine to ram and dump you out to the Wii-U menu/dashboard
Launch your game
The saves will no be dumped over network to the sever directory.
You can now mod them, or stick them on your sd card for loadiine, if you want to put them back once you have modded them, then use the inject.bat and reverse the process