First of all I'm not the owner of this toolchain, so my description could be wrong.(don't blame me plz)
1. Downloading toolchain
You can download expecting toolchain from following URL:
http://www.mikrocontroller.net/articles/ARM_GCC_toolchain_for_Linux_and_Mac_OS_X
2. Install procedure
No need to install it :)
just untar (unbz2 also) the archive like this.
tar xjvf arm-toolchain-macosx-intel-2.tar.bz2
After that you can get your "arm" directory
For me, I moved that to root directory. I mean at the top of filesystem.
Then we have /arm directory.
3. Get included in your path.
you can use arm gcc just typing arm-....gcc if you include your toolchain directory path
in your $PATH environment variable.
Let's assume that you are using bash.
Repeat as following.
vi ~/.bash_profile
and add following line at the terminal of the file.
export PATH=/arm/bin:$PATH
After that you can use your ARM toolchain without typing full path at every path of your terminal.
Enjoy your dev life :)
P.S) I haven't tested on target board whether it is working or not.
I've gotta no arm target board at home ;(