No release is available yet at PyPI so to install the browser two things can be done:
Install Mercurial if it is not installed already and clone the WidgetBrowser cannonical repository:
$ hg clone http://beta.toscawidgets.org/hg/WidgetBrowser
$ cd WidgetBrowser
$ python setup.py develop
If you haven’t got Mercurial installed or don’t want to check out the repository one can install from a development snapshot:
$ easy_install http://beta.toscawidgets.org/hg/WidgetBrowser/archive/tip.zip