you can install this PS2 software emulator to make your PS3 backward compatible. You can download the file here, but before you get started, you may want to make a backup copy of your /dev_flash folder since you'll be replacing some files. As with all hacks, you run the risk of doing damage to your console or wiping it clean if you're not careful or are unsure of what you're doing, so proceed with caution.

Here are the original instructions posted on PS3 Dev Wiki:

1. Replace following files on your consoles /dev_flash/
with the ones included in this archive
p3dwik-ps2compatfiles.rar
2. Get into Factory Service Mode (FSM Tool/Dongle)
3. Insert your Original PS2 Game Disc
4. It will run.

If you don't know how to get into Factory Service Mode, this page should help.

Guys just stumbled upon this old thread (i'm gonna copy and paste the article here to avoid posting links ) and it claims that you can actually add backward compatibility to your PS3 by replacing 3 files in dev_flash , the files are (location in order folder to files)
1.Folder ps2emu...File: ps2_softemu.self
2.Folder: vsh--> module.........Files: sysconf_plugin.sprx and game_ext_plugin.sprx

here's the post:


My question: IS THIS FOR REAL??
Note: this was posted in 2012, but i have never heard about it before