There are actually two problems:
1) easy_install does not run pywin32_postinstall.py. It looks like there is no
mechanism to do this.
2) pywin32_postinstall.py can not be run manually when using eggs since it does
not use pkg_resources.
The second problem is fixed on the pywin32 site by patch 2092722
<http://sourceforge.net/tracker/index.php?func=detail&aid=2092722&group_id=78018&atid=551956>.