[Distutils] Easy Install source download

[Vincenzo Di Massa]

Hi,
I'm developing an easy_install based packager.
It will create distribution specific packages containing eggs. (deb, rpm...)

I would like to generate source packages from which binary egg-packages are 
built.

I spent one day looking at setuptools code, but I did not find how to force 
easy_install to download a source distribution even if an egg is available.

I think package_index has code I can call to download just the tar.gz or zip 
source... but how?

thanks in advance
Vincenzo