The latest Bazaar 2.x application bundles for OS X include Explorer. In some cases, you still need to install Qt binaries separately. See http://wiki.bazaar.canonical.com/MacOSXDownloads for details.
First install QBzr following the instructions here: http://wiki.bazaar.canonical.com/QBzr. Before proceeding, confirm that PyQt is correctly installed by running this command:
Then change to the directory holding your plugins (normally ~/.bazaar/plugins) and run:
bzr branch lp:bzr-explorer explorer
To start explorer, run:
It is recommended that you make this a shortcut on your dock. You can grab a Bazaar logo from here: http://wiki.bazaar.canonical.com/LogoOptions.