[Link: hifi-remote.com]You can use my MakeHex program to translate the device and command numbers from that website into Pronto Hex.
Older PS2's required an IR receiver that was sold with the remote, so you didn't have the option to avoid buying the remote (by generating the right signals with a universal remote).
I read somewhere that newer PS2's have the IR receiver built-in. But I don't know any details. I'm just guessing they still use the same device and command codes used by models that had the IR receiver sold with the remote.