signCheck is a homebrew application that checks if your Wii's IOSs can use fakesigning. This new update adds support for checking IOS 16, 60 and 61 as they are now included in newer firmware updates.
I don't have a wii u anymore to test it myself, but if homebrews are not visible on the wii u menu I think you can press L + R + minus to open the plugin menu, there should be an option called "homebrews on wii u menu" or something similar