You can download the stable script and make it executable. On non-Arch-based system, you may use pacman as script name instead of pacapt.
$ sudo wget -O /usr/local/bin/pacapt https://github.com/icy/pacapt/raw/ng/pacapt
$ sudo chmod 755 /usr/local/bin/pacapt
$ sudo ln -sv /usr/local/bin/pacapt /usr/l...
