Ok so after looking around i found out u can add some extra stuff to you're borderlands all you need to do is browse to the game folder open up DLC folder then POPremierclub then lic and then open the willowdlc doc have it set out to this...
[GoldenKeys]
+SourceId=254
+NumKeys=99
[PromotionalUnlocks]
+UnlockId=1
+UnlockId=2
+UnlockId=3
+UnlockId=4
This will get you all the extra unlocks and 99 golden keys, i also think you can get all the 4 Dlc's for free by just having a doc in that destination folder called SeasonPass all it has on it is the number 2, Il upload it try placing it in you're Borderlands folders if you havent brought the season pass to see if you get it for free