Without having access to run commands on the server, you can't change the IIS settings.
One way to hack it is you can enable Metabase changes in the IIS server properties. This allows you to edit the Metabase.xml file. It would be a considerable security risk, but you can make the directory containing Metabase.xml available so you can download, edit, then reupload. Changes will take affect when IIS restarts. If you made IIS restart nightly, your changes are made. Like I said... a hack.
See: http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/a0ea8e51-fb2a-4e80-9d5a-7fe3ae246570.mspx?mfr=true
However, IIS7 has .htaccess-like features that you are looking for.