There are not many games that support Mouse/Keyboard use for the games, Last of Us or Beyond Two Souls definitely don't.
http://www.amazon.com/dp/B0040UAYI4
There's always this product, that converts Keyboard/Mouse into PS3 controller inputs, but I have no idea to how well it works, have just seen it recommended on other forums and the reviews speak pretty well of it, but they warn to expect that the mouse handles just like the analog stick, not like a mouse does (i.e., moving the mouse faster doesn't move the camera faster, it's a constant sensitivity just like the controller)