Setting writing permissions to a folder.

[Bona]

At ASP.Net application I have a folder which contains the
files, being updated by the users. The application
deployed by Web Setup project. The setup project allows to
set 'Write' permissions for any folder (at IIS level), but
this is not sufficient: it is necessary to set 'Write'
permissions to an ASP.NET Machine name account
under 'Security' tab in 'Properties' for this folder (at
Windows level) as well.
Question: is it possible to set 'Write' permissions to an
ASP.NET Machine name account for a given folder
programmatically, either during setup or when an
application is running?