Pretty straightforward, you need a purple or orange rarity item in each slot. That means:
-4 guns
-Oz kit
-Shield
-Grenade Mod
-Class Mod
Fortunately for everyone who played the game on the 360, if you upload your save from the 360 to the one,and you have a SHiFT account, you get 75 golden keys. For those people who don't know, golden keys can be used on the chest located in Concordia. Each time you open the chest it costs one key and you obtain gear that is equivalent to your level (i.e. if you are level 25, the gear you get from the chest will have a level 25 requirement). You can get everything from here and it will all be purple rated. I'd say could be done in 5 minutes or less this way if you're lucky.
Unfortunately for everyone who didn't, it may take you a bit longer BUT you can still obtain golden keys. Borderland's twitter account gives out roughly 3-5 golden keys every 2-3 weeks, so it may take a little longer but still an easy way to get it done!
If there's any way i can improve this please let me know.