The full information to install ROS indigo on mac can be found here : indigo/Installation/OSX/Homebrew/Source - ROS Wiki.
But just for installation, simply copy and pasted the following commands (full-install)
And note on mac, unlike ubuntu, we have to build up everything from source code. So this is gonna take quite some time
brew update
brew install cmake
brew tap ros/deps
brew tap osrf/simulation
brew tap homebrew/versions
brew tap homebrew/science
export PATH=/usr/local/bin:$PATH
source ~/.bashrc
mkdir -p ~/Library/Python/2.7/lib/python/site-packages
echo "$(brew --prefix)/lib/python2.7/site-packages" >> ~/Library/Python/2.7/lib/python/site-packages/homebrew.pth
sudo easy_install pip
sudo -H pip install -U wstool rosdep rosinstall rosinstall_generator rospkg catkin-pkg Distribute sphinx
sudo rosdep init
rosdep update
mkdir ~/ros_catkin_ws
cd ~/ros_catkin_ws
rosinstall_generator desktop_full --rosdistro indigo --deps --wet-only --tar > indigo-desktop-full-wet.rosinstall
wstool init -j8 src indigo-desktop-wet.rosinstall
rosdep install --from-paths src --ignore-src --rosdistro indigo -y
./src/catkin/bin/catkin_make_isolated --install -DCMAKE_BUILD_TYPE=Release
source ~/ros_catkin_ws/install_isolated/setup.bash
And in order to keep the installation up to date, periodically check the follow commands ( for the full-install )
mv -i indigo-desktop-full-wet.rosinstall indigo-desktop-full-wet.rosinstall.old
diff -u indigo-desktop-full-wet.rosinstall indigo-desktop-full-wet.rosinstall.old
wstool merge -t src indigo-desktop-full-wet.rosinstall
wstool update -t src
./src/catkin/bin/catkin_make_isolated --install
source ~/ros_catkin_ws/install_isolated/setup.bash
The total installation time may exceeds 6 hours, and you may have to type in the user password from time to time while installing the dependencies.
I have encountered a compilation error while installing the rosbag_storage on mac os 10.10. Please follow Error compiling rosbag_storage on Mac OS X Yosemite - ROS Answers: Open Source Q&A Forum for the similar problem.
( it seems that they have just merged the patch for solving this problem in the morning of 2015-5-21. So probably this doesn't matter anymore.)
Some Big Picture
***A very detailed ROS tutorial*** Highly Recommand!!!