No you can't. The PSP is a slave device as well as the camera. A computer is a master device. Slaves can't talk to each other directly. Masters can talk to slaves and other master devices. Do you get what I'm saying? The only way would be to
1) find a diagram for each screen
2) connect the screens to mirror each other
3) write your own software for your camera to tell it how to use the PSP screen
It's harder than it sounds and you risk breaking your camera. Unless you don't value your camera and PSP much, DON'T DO IT!