(((According to todays release notes, this will not be needed for level 4 and above characters anymore.)))
Note: Do NOT go through the Magic Portal to do this, Host your own game. If you go through the portal, you will end up in someone else's game and you will likely be booted. If you get booted, it isn't personal*, but you can avoid that by hosting your own game.
This takes about 5 minutes if you avoid the zombies and only do the minimum to complete each quest.
1. Host a Level I game in Forest Haven and lock it with a password.
2. Step up to Hawken and tap on him.
3. Tap the top button that says "Zombies, Here?"
4. Tap Accept Quest.
5. Kill 1 zombie. White text at the top of the screen tells you that you can return.
6. Return to Hawken and tap on him.
7. Tap on Complete Quest.
8. Tap on Hawken again.
9. Tap on top button "All My Cool Stuff".
10. Tap Accept Quest.
11. Move around the perimeter until you see a chest.
12. Tap the chest and then tap your attack button to smash it.
13. Repeat 11 and 12 until three chests are smashed. White text at the top of the screen will tell you when you can return.
14. Return to Hawken and tap on him.
15. Tap on Complete Quest.
16. Tap on Hawken one more time.
17. Tap the top button "Mr. Swift".
18. Tap Accept Quest.
19. Go to the path on the right and turn two corner. Mr Swift is near the campfire.
20. Tap on Swift.
21. Tap Complete Quest.
22. Exit the game. You can now access the stash.
(thanks, Royce and others)
* = At this time, people are booting almost everyone who joins via the portals. It would be smarter for them to use passwords when hosting, but for some reason, they don't. It's not personal.