You DID understand
Yes. Pick anything up to 11hd and LA +8. You won't get anything out of the HD (feats, skills, etc.; you get your 11lvls of tristalt instead), you ignore them completely, but it's just a way of limiting the critters you can choose from to manageable.
And yes, it's stupid and overcomplicated. More of a thought experiment than a playable game... but we're doing it anyway. Good times. If you have any specific questions you need answered, ask and I'll do my best.
Of note people, we are going to level 1/session. Flat rate. So, kill for the joy of killing, slaughter innocent epic monstrosities and cuddly elder evils, but remember that you're doing it for the sheer bliss of destruction and pride, not for any eeps.
I'm running a story centered game.