If you have a following already, not that hard.
Yes, piracy is a great way to get a forum going but it won't make it interesting beyond the loads of stolen content. Plus it's a ticking time bomb before AK and his crew come in and lynch ya!
You can create fake accounts with some software out there and import users into your database.
Just set scheduled posts and hopefully it'll start to pick up for you. It's work but it can still be done!