Building CHDK requires gcc 4.3.2 and the ARM GCC toolchain.
1. Install MacPorts - http://www.macports.org/install.php
2. Before you install gcc you'll need a working compiler, so Apple's dev. tool (from the installation CD) should be installed.
3. Install gcc v4.3.2. from the terminal, type -
sudo port install gcc43 (type the admin password as prompted) (this took several hours on my macbook pro)
4. Install arm-elf-gcc v4.3.2 - from the terminal.
sudo port deactivate arm-elf-gcc # the above command may give an ignorable error - # port deactivate failed: Registry error: arm-elf-gcc not registered as installed & active" sudo port install arm-elf-gcc # the above command may give the fatal error # "ld: duplicate symbol _init_inline_once in libbackend.a(tree-inline.o) and # tree-inline.ocollect2: ld returned 1 exit status" # still working out how to fix this, but see http://trac.macports.org/ticket/20816 (leads to diff error)
5. make gcc v4.3.2 the default compiler.
cd /usr/bin rm gcc ln -s /opt/local/bin/gcc-mp-4.3 gcc
6. make arm-elf-gcc v4.3.2 default.
cd /usr/local/arm/bin rm arm-elf-gcc ln -s /opt/local/bin/arm-elf-gcc-4.3.2 arm-elf-gcc
From here, the directions for compiling under linux will work Compiling_CHDK_under_Linux although the directions for installing the compiler and cross compiler can be skipped.
Troubleshooting
If arm-elf-gcc doesn't compile, make sure you are using the latest version of MacPorts. To update it, type:
sudo port selfupdate
If that doesn't work, reinstall it from the website. If it gives you an error about libmpfr or something like that, type:
sudo port install mpfr
and try again.