adding --extra-index-url to setup.py setup_requires

Question

I'm building a package with some internal dependency from a local artifactory.

requirements.txt

--extra-index-url http://someurl/
some_internal_package

setup.py

....
install_reqs = parse_requirements('requirements.txt', session=PipSession())
reqs = [str(ir.req) for ir in install_reqs]
....
setup(
....
install_requires=[reqs],
...
)

Any idea how can i add it? is there some pattern for reqs instead of list of strings?