No offense, but I guess you didn't look hard enough as there are links in the Game Consoles section of this site. I don't see any specific instructions for the madcatz 3rd party you mentioned, but there are instructions for digial psx pad.
The madcatz is probably full analog (including the buttons) and as such is going to be a lot harder since you usually can't solder directly to the button contacts (you will have to trace the pads contact to another point to in-which to solder. Sorry but if you are looking for someone to hand hold you though it with detailed descriptions and pictures you are sadly mistaken...you have to LEARN how to do it by reading how its done on similar style controllers. Again, read the FAQ here, and post questions in the console forum.