To compile Colobot on MacOS X, you need to first get Developer Command Line Tools for OS X, which you can get for example from [Apple Developer website](https://developer.apple.com/xcode/downloads/).
After installing Developer Command Line Tools, you should have basic tools like clang and git installed. After that, you can grab other required packages with Homebrew. So as in instructions on [the project page](http://brew.sh/):
Gettext is installed in separate directory without adding the files to system path, so in order to get it working normally, you should call also:
```bash
brew link gettext --force
```
When installing po4a, you might get into trouble over dependency of SGML module for perl. The best way is to install it manually, which requires some changes in SGML's package Makefile. Appropriate instructions can be found [here](http://github.com/oster/PLM/wiki/Po4a-installation-guide-on-OSX/).
If you've installed everything correctly, the simple way of compiling Colobot with CMake should work: