When I was running from my house to a car waiting for me outside, my PSP flew out of my hands and smashed into pieces on the concrete ("first day I ever cried"

) - the joystick was still intact, so I took a look at it and connected it up to my gba.
the joystick was unimpressive when I took it apart, it was basically a rod inside a plastic house with a circle disk and a rubber band/spring.
All I did was basically connect each wire from the D pad point (and the ground) and hook it up to the points on the joystick.
It didn't work properly, only 2 directions worked, not to mention the digital aspect. I always knew it was going to be a 4 points digital joystick before I connected it, but in reality the feeling is absolutely terrible. If you can't get an actual "analog" component to it don't bother.
On a different note, I had one of those "state of the art" arcade joysticks for a Mega Drive. When I took it apart, it was basically just a stick that would press on 4 heavy switches, if you wanted diagonal it would press on 2 of the switches at the same time, lol. Clicky rubbish it was, no good for Fireballs!