If you get a 747, 746, 16a (I think its the 16a that does the airport route)....get off on the last stop on Dorset Street then turn right up Blessington Street...keep right and it becomes Berkley Street...5 minute walk....
And if you don't know the area, theres a hidden gem of a park at the top of Blessington Street called the Basin Park....It used to be the water resevoir for central Dublin...beautifully maintained by Dublin corporation...
Sorry..I digress......Don't get on any 41 buses as they go down Gardiner St and will take you away from Berkley St. direction...