First, log into the game and type /console in your chat box. This opens the Console, you can now use ~ to open and close the console no matter where you are until you close the client.
Next, go to the character selection screen (all of this also works at the re-customization NPC if you're modifying a currently existing character) and enter the console.
The command you need to use is "costumecreator.randomecostume 1"
The results are random, so continue to enter the command (hitting the up arrow and enter will allow you to repeat this process very quickly) until you get the desired results.
Unique skins will be produced. Have fun.
These skins are server side and will be visible to all players.