[Request] - Dwarf Male to Undead Male 1.12.1

[koitik]

Hello

I am very new to the whole model editing, but I really want to change my Dwarf Male to an Undead Male.
I've tried a few things, like editing the mpq file, but the texture of my face is really bad (see the image below)


I'm playing on a 1.12.1 server, and Ive seen this guy play on the exact same server, and he has found a way to work around the issue (you can watch this youtube clip below)
https://www.youtube.com/watch?v=NENsoOaM7xc

If any of you could guide me, it would be greatly appreciated!

Thank you in advance.