All of the names should be right there together; they only appear in one place in the ROM. They are inside a compressed event packet (so I suppose its possible the names got compressed away). Lucca's name, IMS, has a sub-packet header in the middle of it. You will need to edit around that header. Each name is six characters long ("Robo" followed by two null characters). Editing it by hand in a hex editor will be tricky, but I think it should be possible. I have not looked at the raw bytes anytime recently though, so I do not say that with confidence.
---T.Geiger