Yes, it can be done as a spot treatment on dilated pores, acne scars and any other type of scars (surgical or non surgical).
Because the 1540 is an erbium laser skin color change should not happen. Spot treatment of dilated pores, acne scars and other types of scars can certainly be done.
In general, it is best to treat an entire face for best results. However, if you are using the Lux1540 to treat pores, for example, you may consider doing an isolated treatment of the T zone. I would not expect a difference in coloration as a result of treatment.