How to swap disc to disc 2 in RetroArch?
How to swap disc to disc 2 in RetroArch?
If you still require help you need to hit F1 then scroll to where it says Disc Control , it should be self explanatory from there.
THE BEST METHOD to run PSX games (and everything else for that matter) is via Retroarch - http://buildbot.libretro.com/nightly/
If you have any questions on how to set it up on Windows please feel free to ask, its very easy.