For me, the easiest way to beat Dante was to jump onto the dias in the center of the room. Dante may start shooting you with his guns at first but soon he'll try to jump onto the dias to join you and fight. While he's jumping, use a Buster on him, and you'll slam him back to the ground. When he gets up and jumps up again, just use another Buster. And yeah... just keep doing that :]
It's not the most stylish way, but you should be able to keep doing that wihtout dying. Hope this helps.
p.s. Yeah, i have the 360 version too. It's pretty good eh? n_n