How to create 'fake' users?

I'm configuring and testing our EPDM installation and I need to create some fake user accounts with various permission sets in order to test the setup before rollout.  The problem is that the system is set up to use Windows logins for users (much more convenient for real users) and it won't allow me to create any users that aren't already listed in the server.  That means the only way I can test using these accounts would be to gain access to some users real passwords, which is certainly not an option.

Is there a way to set up the system so that I can create real users with Windows logins and also fake users for my own testing purposes?