Service 747 runs non-stop to O'Connell Street (where many people get off because that's where the tour buses run from). It then continues, non-stop, to Bus�ras (= Dublin Central Bus Station), which is close to the southern end of Lower Gardiner Street.
Here's a map for you:
http://i27.tinypic.com/2wq4wp3.jpg
O'Connell Street runs roughly north to south, down the middle of the left-hand page. Lower Gardiner Street is roughly parallel to it, on the right-hand page. Bus�ras is towards the bottom of the right-hand page.
Chris