Yeah, it was kind of crazy, but I wouldn't say the first 3 parts of the story is essential:
It started with a crossover in the middle of OMAC Project with the then 3 Superman books, with a 4th chapter that crossed over into Wonder Woman, with the story then being picked up back in Omac Project #4.
The first 3 chapters are a mind-frelled Superman beating up those Lord deems enemies, which is successful until he sends Superman at Wonder Woman. She works out he's behind it, in a confrontation, Lord does the usual 'you can't save Superman without killing me' taunt, so she kills him!
To be honest, I found both Batman and Superman to be dicks about it all to her afterwards. There was a far better follow-through on the consequences of it all in an arc Andreyko's Manhunter run.