You'll probably have to buy a memory card that connects to computers via USB. That's how people upload game saves on GameFAQs and stuff. The drawback is that the person who wants to use them has to have the same thing as the person who uploaded. Codebreaker saves are incompatable with Gameshark saves and vice versa and same goes with any other USB-uploaded memory card saves. As to how to modify it, again I don't know. Try to find a forum that deals with this stuff, some gameshark forum or whatever.
Not a memory card. Just a USB flash drive and a Code Breaker. Also, PS2 Save Builder can convert saves for any PS2 save transfer product to saves for any other PS2 save transfer product. It's downloadable at
www.ps2savetools.com