Per the following article, we need to know the specific Security Capability setting that will allow a user to add a new path.
http://www-01.ibm.com/support/docview.wss?uid=swg21342666
Just like how you can configure certain user groups to Schedule a report, or to have access to Report Studio, does adding a File Location have its own admin Security Capability?
5. Click the Define File System Locations button ( top right)
6. Click New
I don't see a specific capability for this. My guess is it falls under the "Configure and manage the system" capability under Administration. The linked article states "an administrator must then set the file location in Cognos Administration" so this is probably something only the System Admin or Server Admin roles should do