The easiest way to install Tesseract OCR on Mac is using Homebrew. If you don't have Homebrew installed, just go to Homebrew's site (http://brew.sh/), open your console, and run the Ruby script that is on the front page. You may be required to type in your administrator password.
After Homebrew is installed, just type in the following:
brew install tesseract
The English language is already included in this installation. If you want to install other language packs, just run the following command:
brew install tesseract --all-languages
This will install all of the language packs. Then, just go to the Tesseract installation directory and delete any unwanted languages. Homebrew usually installs stuff in the /usr/local/ ...