Sony has changed the bios after March 08 and fix the critical defect which allows programs like FMCB to boot PS2 using memory card.
The only options are...
- Use Swap disk : I'm using Swap Magic 3.8 and it works fine with most of the games. http://techvision011.blogspot.com/2009/07/how-to-user-swap-magic.html or http://www.youtube.com/watch?v=McMgFkHpeV4
- Mod Chip : I don't recommend Mod Chip unless you don't have any other option as this will void your PS2 warranty.