I finally understood what he want, according to his post today:

" Hey, here’s an idea… using the VFS wrapper idea our
‘ports’ system could create a namespace that makes everything
appear to be preinstalled. So instead of CDing somewhere and
typing make, or running an apt-get type of utility, you would
simply run the program you want to run and our package manager
would download and install it on the fly."

This is something like what Microsoft has done with Windows Installer :-) However, Microsoft’s approach is based heavily on IShellLink::Resolve to execute install on demand.

Well I have to say that I just found Windows Installer 3.0’s documentation, so, study more and study often, as technology is growing everyday…