Four companies of the 5/60th (well 3 and a cadre - 327 effective rank & file) landed at Cobh on 20 April from the Medusa and Ulysses transports, along with the Hompesch Mounted Riflemen (358 effectives). The rest of the 5/60th had been formed on Barbados and the companies that landed in Ireland came from the Homspesch Chasseurs who had been on the Isle of Wight. The 5/60th went to Wexford and fought at Goff's Bridge, Lacken Hill and Vinegar Hill.
Full detail of the units in Ireland at the time of the rebellion are, of course, at the The National Archives. For example WO 17/1160 gives the location of every regiment, including those in Ireland but Ireland only returns are also available.