Until they come up with an installer for OS X, these are the steps to update (upgrade) or re-install LetsEncrypt on the Mac OS X
Operating System, Mac OS X Mavericks.
1. Backup the current LetsEncrypt directory. If something goes wrong, you can just bring it back the way it was before.
[server:~] root# cp -R /Users/AdminUser/letsencrypt /Users/AdminUser/Downloads/install/LetsEncrypt/backup/12-01-2015
2. The installer will not install or replace the directory, so Delete the current LetsEncrypt directory on your AdminUser profile. So, (as root);`
[server:~] root# rm -R /Users/AdminUser/letsencrypt
3. Now, with the AdminUser root directory clear, Run the installer (as Root)
[server:~] root# git clone https://github.com/letsencrypt/letsencrypt
Cloning into ‘letsencrypt’…
remote: Counting objects: 28778, done.
remote: Compressing objects: 100% (66/66), done.
remote: Total 28778 (delta 34), reused 0 (delta 0), pack-reused 28712
Receiving objects: 100% (28778/28778), 7.56 MiB | 292.00 KiB/s, done.
Resolving deltas: 100% (20238/20238), done.
Checking connectivity… done.
Now you have the latest copy of LetsEncrypt installed in your machine.
Ps: This have been tested on my Mac and is working just fine.