Step 1: You need...
one pair of mp3/mp4/ipod portable speakers
-i prefered to use mp3/mp4 speker because the ipod speakers are much more expensive. these cost 10$, ipod speakers much more.
-try to find speakers with builted in amplifier. placing a speaker directly into to the jack won't be louder than the psp speakers.
Step 2: Tools
hot glue gun or something similar
and other that are not imperative
-try to use a small drill for precition
-you will need alot of glue to keep all the parts togeter, because i didn't used screws.
Step 3: Working on the joystick
-measure everithing twice before cuting. it would be ashame to buy another joystick
-allways work on the edges. roudn everything up so that you won't damage the psp
-the joystick is also plastic, and it won't scratch the psp if there aren't sharp edges
Step 4: Working on the speakers
place the amplifier on the back of the psp
-use a soldering wire to remove wires, or to patched them
-if the wires are to short add some more wires
-cut with the drill the speakers and the joystick so that you can find a nice place for them
-don't discard any materials.. you might use them later (pic 1)
-the amplifier can be placed paralel or perpedicular to the joystick. if it sticks out, then you will have a larger unit, but it can function as a video stand for watching movies.