1. Download OpenEmu Experimental from http://openemu.org/ and unzip it
2. Download bios from http://www.theisozone.com/downloads/playstation/other/sony-playstation-bios-package/ and unzip it
3. Open OpenEmu drag SCPH5500.BIN and SCPH5502.BIN into OpenEmu
4. Rename SCPH5552.bin to SCPH5501.bin and drag it into OpenEmu rename files follow the md5 chart
5. Download roms and have fun :D

http://mednafen.fobby.net/documentation/psx.html