So like me, you need to kill Jimmy Jenks to get the achievement for completeing all level 1 challanges.
Don't have Creature Slaughter Dome, and you are past the mission Doctors Orders
Fear not, here goes another way to get good Ol Jimmy Jenks to show up.
First go to The Bunker in thousand Cuts
Save your game.
Go back into Thousand Cuts... You should see 4 chest and a loot chest next to the door you exit.
Open them, cross fingers. No Jimmy, head on down the road to a set of steps on your left.
Climb steps you should see 12 more chest to open, 3 of them will be weapon chest.
If you don't get lucky, go back into the Bunker, Save and Quit.
The only thing to worry about is the Badass that will spawn as you climb the steps. Shouldn't be too much of a problem though if you can kill other BadAsses and have the ability to kill the loot midgets/loaders/Jimmy
I'm not sure if he or the other loot midgets have a chance to spawn in the Bunker which could also increase your odds quite a bit.
Make sure to save/quit inside the bunker so you don't have to make the run all over again.
Sorry if I could Dupe Jimmy Jenkings for you I would...