[Question]PSP as an extra PS3 controller?

I only have 3 PS3 controllers, but my friend has a PSP that's legit, clean, not hacked or anything. So is it possible for my friends and my to play a game (MW 2) together on splitscreen using the PSP as a 4th controller?

That would be a no, as the PSP is missing 1 Analog stick and both the back triggers, and even if it could your friend would be at a major disadvantage when playing

ok. thanks for letting me know.