I installed nkf on Mac using Homebrew.

% brew install nkf                     
==> Downloading http://dl.sourceforge.jp/nkf/53171/nkf-2.1.2.tar.gz
######################################################################## 100.0%
==> Patching
patching file Makefile
==> make
==> make install
/usr/local/Cellar/nkf/2.1.2: 4 files, 252K, built in 2 seconds

Easy peasy!

That’s all from the Gemba.