I've been playing NMRiH for a while and I recently noticed that it was packaged the same way as Insurgency when I was actively making mods. Just to test to see if it would work the same way, I made a re-skin of The Hunter with a couple of anime graphics of my favorite character Chitoge Kirisaki, from Nisekoi.
I also included a zombie re-texture for when you become one of them.
There was a pretty big lack in re-textures (well then again, I didn't search too hard), so I figured I'd start making a few anime-themed contributions for those of us who would like them.
As for the changes, I've added graphics to:
Jacket
Inner Shirt
Baseball Cap
Jeans (Cell phone keychain)
Neck Tattoo (though it's difficult to see in-game)
The vpk can be downloaded at:
http://www.mediafire.com/download/89psr8vyvgn0f5l/chitogehunter.vpk
To install the mod, it can be done in 3 easy steps:
Go to your steam folder Steam\steamapps\common\nmrih\nmrih\custom Drag the .vpk to the custom folder
I've never touched the game files until now, so I'm assuming that this is the only thing you need to do to install it.
If you have any questions or issues, please post below and I'll do what I can to help.