Can setup.py copy modules to a location other than /usr/share/ansible?

Not sure I'm fully following you here, but you should be able to do a
simple 'git clone' or download the src.tarball anywhere you want and run
ansible just fine after you running the 'hacking/env-setup' setup script,
which sets a few vars for it. No need to install with setup.py.

Also try installing with pip under virtualenv.