First you need a set of supporting libraries; these can be built with some scripts fetched using:
git clone git://git.carlh.net/git/osx-environment.git
cd osx-environment
Adjust config.sh to suit your machine; you need the SDK for the OS X version you are targeting (I use 10.6) and an installation of CMake, and config.sh must point to these things.
Now you can build the libraries with:
./download_all
./rebuild_all
Finally, install cdist using:
git clone git://git.carlh.net/git/cdist.git
then copy the cdist script somewhere onto your path (e.g. /usr/local/bin).
cdist needs a file ~/.config/cdist which should contain something like:
osx_build_host 10.6
osx_environment_prefix /Users/carl/osx-environment
osx_sdk_prefix /Users/carl/SDK/MacOS10.6.sdk
git_prefix git://git.carlh.net/git/
Finally
cdist -p dcpomatic -t osx package
should package the git HEAD of DCP-o-matic for OS X.