Using Bazaar on MacOSX is a cinch with Homebrew all you need to do to get started is:
1. In Terminal paste the following:
ruby -e "$(curl -fsSL https://raw.github.com/mxcl/homebrew/go)"
2. Then install bzr from Homebrew: brew install bzr
3. Define where Python is using the following command: export PYTHONPATH=/usr/local/lib/python2.7/site-packages
Then you should be good to go!