Ok, I went ahead and ordered the adaptor at EB. Only thing is, it doesn't work with the third party digital controller I used. It does work with the official dual shock, though (of course). In order for the dual shock controller to be recognized, I have to make sure that the analog is switched on. Otherwise the dual shock doesn't work either.
So I think what I have to do is hack an analog psx controller. Is this what your friend did, Snake? I bought a 3rd party analog controller that works on both ps1 and ps2. It doesn't work either! Should I use a dual shock, even though I hear it's hard to solder to? Any suggestions are greatly appreciated.