Gotta buy the files from PWI (or sketchy russians)
Contract with PWI = 40,000 and they have to have advertisements for the main server (PWI) on your private server
If you obtain files, host server as 1.5.3+ without PWI's consent they will sue you and get you shut down.
It's all licensing issues guys, and at the end of the day, you don't want the new classes. They're trash, they ruin the game.
Give us everything except new classes xD