How the f...Did you manage to do that?
Can you actually play it on your ps2?
WTF HOW?!??!?!?
It's exactly the same as the pc version... create a lua script, compile it, replace it in scripts.img and that's it.
You will need apache to replace the content (in this case scripts.img and scripts.dir) from the iso file... you can't do that with the windows explorer. The only downside is that unlike the pc version, your script must be smaller than the script you are going to replace. Let's say I want to replace ArcRace1.lur (8 kb) with my compiled lur script (10 kb)... this will not work.
This works on ps2 if you burn the modded iso to a dvd, althought I'm playing it on pcsx2. If I remember correctly walter told me that he made a local multiplayer mod for his ps2.
Btw I found some weird differences in the ps2 version.