Welcome to Gaire. Cruising can be a dangerous activity, and if it results in sex in public is illegal.
Having said that if you want to give it a try you should look up www.squirt.org
You can meet people through the classified section here or on www.gaydar.ie
You'll probably be disappointed if you're hoping to meet people on the street or in some random cafe.
You could also look up outhouse on Capel Street. They host lots of clubs for gay types, most of which don't involve alcohol.
Good luck with your search, I hope you meet someone nice.