Put your mouse over a cabinet in the detail room and the number pulse info show up to the left below the grid setting. You could take the room to the line drawing editor and use the note option to number them then print it out for your installers. Also the cut list has the cabinets listed by there number.
Bob,
You can take your layout to the line drawing editor, highlight them then right click, choose add cabinet # or something to that effect, couple different ways of doing it once you get to lde.
hth