Coruscant
Enter The Works via the northern Justicar Territory entrance. This will bring you the Hydrosupply area.
Head south and stay on the southern path through the Primary Junction Room. This will take you to Automated Maintenance.
Around 1069, -2302, head East. Do not go down the ramp, instead follow the path around the bend and head up the other ramp. This will take you to the Pipeworks Passage. Follow it to the easternmost wall and then north. Pass the Cthons to end at 1171, -2280. The crates here are your entrance to the secret path, and will give you access to the 45 degree angle pipe that's running up along the wall.
Turning Sprint OFF during this pipe portion makes it easier for some.
Follow the pipe up, and jump to the next one.
When you get to 1030, -2277, face south and jump to the new pipe. Follow this until it bends down again. You should see Wounded Soldiers below. If you turned Sprint off, you may want to turn it back on for this jump over to the next one.
Keep on trucking... up, up, up, then down to the lower one against the wall at 994, -2270.
You will come to a platform. Take a breather, then cross the platform north. You will be able to see the Datacron clearly, and the skinny pipe that leads to it. You don't need to step off where the pipe meets the platform, but it's your call. Grab your shard at 950, --2292. And grats!
Empire:
Dromund Kaas - Galactic History 18: The Hutt Cataclysms
Republic:
Coruscant - Galactic History 06: The Infinite Empire Collapses
Both:
Nar Shaddaa - Galactic History 36: The Quarren-Mon Calamari War
Ilum - Galactic History 86: The Empire's Revenge