$ sudo apt-get install bzr
$ mkdir schooltool_test
$ cd schooltool_test
$ bzr branch lp:~schooltool-owners/schooltool/ark schooltool
$ bzr branch lp:~schooltool-owners/schooltool.gradebook/ark schooltool.gradebook
$ bzr branch lp:~schooltool-owners/schooltool.lyceum.journal/ark schooltool.lyceum.journal
$ cd schooltool
$ make ubuntu-environment
$ make develop
# EDIT buildout.cfg with the following changes:

develop = . ../schooltool.gradebook ../schooltool.lyceum.journal

[versions]
# Unset versions of packages you want to develop
schooltool =
schooltool.gradebook =
schooltool.lyceum.journal =

[package]
eggs = schooltool
       schooltool.gradebook
       schooltool.lyceum.journal

$ make instance