Get a printer and those disc-size stickers, and print any logo u want on the sticker.
If you mean the "PLAYSTATION 2" on startup, i think u need to modify what the BIOS sends, Just like Matrix modchip does, a tiny version number next to the logo. I presume that every game sends some call to get the logo to appear. So, just hack an Matrix firmware and buy the chip, or make a data sniffer chip that redirects the logo calling to your own logo.
There's no ready tools for that what i know of.
I'm installing FMCB in Finland. I'm installing modchips for PS2, Xbox360, Gamecube and Wii, in Finland. I live in Finland.
I love Finland. My country is Finland. I work in Finland. I was born in Finland.