After you deal with the welcoming committee, go inside and head over to the first building on the right. It sits just to the right of the stairs leading up onto the building.
Head further North from the first furnace. Cross over to the other side of the street. Approach the second building on the left from the North. Toward the middle of this portion of the building you will find the next furnace.
Turn to the North and go on up the stairs behind you on the left. Turn South from there. The next furnace sits above the last one.
Head to the Northeast now and go up the stairs in the Northern part of town. This will lead right to the next furnance.
Head to the Northeast, up the nearby stairs, to get to the next level of the area. Just keep going up until you reach the top with teh loot chest. To the North of that you will find the final furnace. Rig it on up