Step 1. Make sure you have a copy of Grand Theft Auto: Liberty City Stories UMD. Then see if it has a 2.00 update on it, or a 2.60. If you have a 2.00 update on that umd, you can do this downgrade! Otherwise, stop here for now.
Step 2. Grab a copy of Noobz's 3.03 Downgrader
here, a copy of
1.50 here, and a copy of
3.03 here.
Step 3. Upgrade to
3.03.
Step 4. Install the
3.03 Downgrader by unzipping it to the root of your memory stick (Like to E:\ or G:\, where your psp is).
Step 5. Grab your copy of the
1.50 EBOOT.PBP, rename it to UPDATE.PBP, and move it to (/psp/game/UPDATE).
It should now be (/psp/game/update/update.pbp).
Step 6. Start GTA. It should get to "loading savegame", then the screen will clear to black and fill with a light blue color, then the PSP will reset itself.
Step 7. Check that HEN is running by going to "Settings", "System Settings", and "System Information". It should now be "303 HEN". If not, go back to
Step 6. Step 8. Go to "Game", "Memory Stick", and run "Update x.yz". If your motherboard requires patching, it will be automatically patched, so don't worry about it. Press "X" to begin the downgrade.
(If it comes up saying that the settings are corrupt, press x to continue. Load the included NetConfigBackup application in your PSP, and select "restore", this will restore the backup of Network Config done automatically during the downgrade.)