There's a couple of "phat loot" mods on the steam workshop, though they may not work with the current patch. You can easily modify the treasure tables for lucky charm (at the bottom of the treasure table text) to always proc on a container and give you 5 legendary items every time. You'll probably also want to modify the "itemtypes.txt" file to make legendary items drop before level 5. Frankly I don't know why you want to do that because the game is not at all balanced for characters fully decked out in the best legendaries you can find, but if you want, it's not that hard to make the changes yourself.
See this thread for a general intro to modding stats (though it doesn't really talk about treasure tables specifically, it'll get you started).
http://steamcommunity.com/workshop/discussions/-1/616198623973649136/?appid=230230 
