Hi, the installer was designed to work on windows only. But the RP manager can work on mac too.
Install node.js Mac OS X Installer (.pkg)
novaskin.zip (19.3 KB)
extract this zip file to the minecraft resourcepacks folder, inside a novaskin folder (just like a normal resource pack)
run this command inside the bin folder
open this page to check if it is working
You should see this message
you will need to run the command manually, but I will try to make a mac and a linux installer soon
the same works for linux, just install the nodejs version for your system.
the windows version runs in background as a service