Someone kindly entered the locs for the robes on eq2i:
http://eq2.wikia.com/wiki/The_Heart_of_Treachery
You can go to
http://maps.eq2interface.com/ and put in the locs so you can see on the map where you're going.
In Seb:
Drop down to the water tunnels - you want to invis through and hop into the closest pool, it'll take you into the jail area. You'll go straight through there, around the corner, up a ramp through a set of gates - veer to the right from there.
You'll take the first left in that room, and if I'm remembering correctly, you'll end up facing a set of stairs into a room with a bunch of sathrians, pathing guards with chokidai and a crypt juggernaut or two. 5-7 min repops on mobs so you need a good group (most mobs see invis till the actual room with the robe). If there's a corner, it's a safe bet there's a mob on the other side of it.
In that room, you want to head straight to the back wall and turn to face the room on your right. The robe is in a box on the table directly across from you on the back wall.
I went down tonight solo to see if i could get in there, ended up joining a group who was already there. It was hilarious & complete mayhem down there. Pretty much: one group would wipe, the other would fight the mobs and rez, they'd get jumped by extra mobs, wipe, the other group would fight the mobs and rez.
I recommend a brigand party: 24 brigands with revive tokens storm the barracks. Turn your sound up when you do, the sound of 24 tweety bird effects from all the cheap shots going off should be a hoot. :D
Everyone gets their updates in one batch! ;)