Buy your train ticket (to Belfast) ASAP as the fares were €9.99 (each way) yesterday and rise as you get closer to the day of travel. They're €15.99 each way today, and will keep going up!
There's a station at Hilden Halt but coming back the connecting train will leave you waiting almost an hour in Lisburn for the Dublin train, so it's no real use. Just walk to Lisburn Stn from Hilden instead. It's about half an hour walk.