MacOS isnt officially supported anymore, however its still possible to build it and make a HexChat.app bundle.
So here it is for convenience.

Simply extract the zip and copy HexChat.app to /Applications/

Notes:

• Python2.7 support
• LUA support
• Perl support
• OpenSSL 1.0.2j

Update 09.10.2016 As of HexChat 2.12.2 , these features are merged and included !
Get it here https://hexchat.github.io/downloads.html or https://github.com/hexchat/hexchat/releases

Features added:

• Diffie-Hellman Key-Exchange (DH class taken from the guys over at https://github.com/hdznrrd/mircryption-xchat2 as its clean and uses "openssl/dh" , thx!)
• commands
  • KEYX [], performs DH1080 key-exchange with \
  • TOPIC+ , sets a new encrypted topic for the current channel
  • NOTICE+ <nick or #channel> , sends an encrypted notice
  • MSG+ <nick or #channel> , sends an encrypted message if you already keyx'ed

PS: the remote exploit with /keyx due to a overlong key that affected XChat/XFiSH is tested and NOT possible

PR pending hexchat#1440
Update: PR got merged !!