Without any hesitation, let's get started!
You will need:
*Mac with Snow Leopard (Other versions are untested)
*Internet access (Already got)
Step 1: Downloads
Step 2: Install 'PCSX'
Double click 'PCSX-test3.dmg' to open and mount it.
When it's mounted simply drag the 'PCSX' file into your applications folder.
Read the 'ReadMe!' file for information, it's not that helpful but read it anyway.
Now un-mount the disk image. - Click the little eject button after it's name.
Step 3: Install the PS1 BIOS
Now, close PCSX. This step creates the neccesary location for us to put the BIOS files into. (EDIT: Thanks for pointing it out uselessparadigm)
Now to install the PS1 BIOS.
Double click 'Playstation Bios Files.zip' to unzip the folder.
Bring up a new finder window and navigate to:
Your user account name e.g. 'spikematthewspadley'.
Now take all the files that were unzipped from 'Playstaion Bios Files.zip' and drag them into the Bios folder.
Step 4: Open PCSX
So open up PCSX.
Go to the top menu bar (See picture)
And choose 'PCSX' - 'Preferences'.
Now. You want to un-tick the 'Dynarec CPU core' option.
Step 5: Almost there
Take your PS1 game.
Put it in the CD drive.
Go back into PCSX
And in the menu bar click (Photo)