I put this in my WebApp's web.config file:
<processModel enable="true" userName="toto" password="toto">
I modified machine.config too to allow this parameter to be redefined

But when i execute any script in the same webfolder, it is still executed
as SYSTEM account.

I'm not sure this section is destined to what i want to do.
I want to build a free hosting web server and then scripts from "toto" must
not have access to "titi"'s files. Then for each account, i create a windows
account and a folder with access only for admin and the member owner.

Is it the Right way ?