I have done a little skin that looks good on the black NDSL.Probably on other colours to!I made this skin using Omgwtfisthat's Vista skin as a template.
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