Create a shared remote bzr repository:

bzr init-repo --no-trees sftp://development@server.example.com/srv/bzr/project/
bzr init sftp://development@server.example.com/srv/bzr/project/trunk
bzr co sftp://development@server.example.com/srv/bzr/project/trunk project

The docs all create a repos in /srv/bzr in which branches are created, but to me, it seems illogical to put all your projects in one repository. So, I create one per project.