To unlock this vendor, do two quests. The first is the prereq quest Highway Robbery
http://ffxiv.gamerescape.com/w...
The NPC that gives this quest is at Limsa Lominsa. From Limsa, take the aetheryte to the aftcastle and go straight east to find him.
The second quest can be any of the Kobold quests (all the quest givers are standing next to the vendor.) The Highway Robbery quest will leave you in the center of the Kobold people, and there should be an immediate quest waiting for you.