I love From Software, I recently bought the DLC for the PS3 version of Dark Souls (I beat Demon's Souls over 4 times, and Dark Souls once) and can't access it until I kill the Four Kings on NG+. It's damn hard, but I love that they make you work to access it.
You can access it directly after you place the Lordvessel, the key is in Duke's. ;)
Anyway, I'm doing a full base SL playthrough where I record myself beating bosses with a ruleset (no healing, no elemental weapons, only one piece of armor but mostly naked). Channel is here, if interested: https://www.youtube.com/user/bethannpoptart?feature=mhee
Going all the way through the DLC and final boss!