If I remember right, plug the card into the cabinet and make a note of the cab, shelf and slot, log into the CDE forms on the switch and select single line set assignment form from the single line set forms menu, scroll down the cab shelf slot column until you see the position you made a note of earlier it should show the card with empty directory number column, if you have gone in edit mode you can add the extension numbers you want and the other columns which on my switch are all 1
Good luck
Tony