For those unfamiliar with the location of the non-canon footlocker, I have posted a guide on how to reach it below. It's hidden using spoiler tags, so those who want to find it themselves can do so.
1) Go to the Dreshdae Civilian Quarters.
2) Go to the Miner's Lounge. It should be obvious which room this is, but for those still unsure, refer to the minimap.
3) Speak to the "drunk" miner at the back of the lounge. You will notice he strongly indicates that he isn't fond of losing a game of Pazaak 3 times in a row.
4) Beat him 3 times in a row, and he will then leave the Miner's Lounge.
5) Follow him as he moves through the Civilian Quarters.
6) He will eventually stop and open a door which was previously locked. Inside this room is the non-canon footlocker.