If you're following the rules, then unless you're playing an army that specifically allows you more than 2
HQ choices, you can't. Of course, if you can get your opponent to agree then that's fine. You can field T10, W10 Guardsemn with S10 AP1 lasguns if you get your opponent to agree.
FourCartridge wrote:Thought I read something about detachments that allowed you to write separate lists for higher point games in the core rulesbook though.
Well, that is possible, but it's not common. I have never seen multiple detachments fielded, except in megabattles where such things were previously arranged. If you should up to game with a multi-detachment list...I'm not sure I'd be willing to sit down and play them. The
FOC is there for a reason, you're not supposed to go beyond it.