Thanks for your comment. In Active Directory Users and Computers did you click on View (at the top) and select Advanced Features? And Attribute Editor is on the general tab, it is just a button and not a Tab.
Thanks for the info. I wasn't able to get the "EDIT EMPLOYEE NUMBER IN ADUC" section to work. Added an existing schema item to extraColumns, but then when right clicking on user, didn't see it. Also didn't see a tab called "Attribute Editor"