Ugh, I had a heck of a time with that one too. I don't know why it was so hard to locate, it is just sitting out there.
On the mini-map, it's on the building to the immediate Northwest of the GCPD building. It'll be located on the east side of the building. The building has a large GOTHAM neon sign facing towards the sea, and if you sit on the Northwest gargoyle on the GCPD building you should actually be able to see the CCTV console.