There is access to O'Meara Camping from Crumlin Road, opposite The Gate Bar.
There is NO access to O'Meara Camping from either Brickfield Drive, or Keeper Road!

If getting a Bus from Dublin City Centre, there are three buses that will bring you to O'Meara Camping.  27, 77a, 151. 
All can be boarded / hailed on Dame Street, across the road from the Olympia Theatre. 

When using a Sat Nav, direct the Sat Nav. to Unit 4, Sunshine Industrial Estate, Crumlin Road, Dublin 12.
This will bring you to the gate of Sunshine Industrial Estate. As an alternate put in to the Sat Nav.160 Crumlin Road Dublin 12.