Catch a rat inside Gunthak's Shanty ( -1270, -953, 635 ) /waypoint -1270, -953, 635 (double-click a rat). You must NOT be invisible or you will not get the charm.
Use the rat illusion item in your inventory while standing on the pillows at ( -1248, -933, 459 ) /waypoint -1248, -933, 459
Kill Momo the monkey at ( -1263, -936, 448 ) /waypoint -1263, -936, 448right behind the building. He is on a 5 minute respawn timer.
Some AoE CAs, especially pounce, tend to pull aggro from surrounding mobs, so be careful. After you kill Momo nearby monkeys may attack, clearing nearby monkey mobs may prevent this from happening. If you do die after killing Momo you return to your own body - double click on another rat, assume its form and continue to the next step.
While in rat form slip through the wooden boards and kill the ornate chest in the store room directly behind Momo
Drop the rat illusion and click on the ship's wheel ( -1318, -932, 501 ) /waypoint -1318, -932, 501
Note: Exiting the zone via the ship's wheel ports you into the middle of hostile NPCs. If you have the Brokenskull Officer Disguise from A Higher Purpose, you should make sure that is applied prior to leaving. Otherwise, consider using some form of invisibility before clicking on the wheel to leave, or use evac/ call out.