You may list hexagonit.socialbutton to buildout.cfg or setup.py of your own package.
Use zc.buildout and the plone.recipe.zope2instance recipe by adding hexagonit.foldercontents to the list of egg:
[buildout]
...
eggs =
...
hexagonit.socialbutton
You may also list to install_requires to setup.py within your package:
setup(
...
install_requires=[
...
'hexagonit.socialbutton',
...
],
...
)