You can use the Mouse and Keyboard on PS3 in similar way as on PC with 2 limitations though:

1. There is no PC style hotbar(s) available, only PS3 crossbar
2. There is no Mouse + Keyboard / Controller "flip" swicht in the character settings screen

You also would need to toggle off in the setting the direct chat option to be able to use keyboard for the character movement. To type in the chat you'd then need to always first press enter however you'll gain a benefit of Strafe Left / Right via Q and E buttons.