Adding a Printer for All Users

To add a shared printer that all users of a workstation will have access to.

Do this as a user with local admin privileges.
Open a command window and enter the following:

rundll32 printui.dll,PrintUIEntry /ga /n\\computername\printername

Adding a /c\\computername parameter to the end may make it possible to do this over the network (assuming the user you are logged in as has local admin privileges on that machine).