I would like to bootstrap a virtual environment from a local web server. Not being able to specify an alternative 'download_base' from the command line for 'distribute_setup.py' when invoked as script makes this harder.
I changed the command line options handling to use 'optparse' which should be supported from Python 2.3 to 3.3 although deprecated having been in favour of 'argparse' from Python 2.7 onwards.
A new command line option '--download-base' was added that allows specifying an alternative base download URL for the distribute package from the command line when invoking 'distribute_setup.py' as a script.
One thing I might change about this is keep the argv argument in main(), and pass the argv to parser.parse_args(). Not that it's likely to be an issue here, but I always use this pattern since it can be useful for testing (you can test main() without having to mess with sys.argv).