Driving from Dublin: Take the N4 to Longford then exit to the N5. This will take you right into Castlebar. This is about a 3 hour drive.
There is a train directly from Heuston Station in Dublin, it is the Westport line, Castlebar is the second to last stop and the journey is approximately three hours. Go to irishrail.ie for more information.
Driving from the South: Take the N60.
You can also fly from Dublin to Knock Airport, which is a fairly short drive 32km.
There are also three buses a day from Dublin.
