I don't think slave scanning was coverd, if you had a few slaves you could "Dos" the target with SYN connections, a weak DoS which will be writen off as a bunch of kiddies messing around while in acctuality, it's been one person scanning through several zombies.

I don't know much about Zombie scanning, but in theory, that should confuse the hell outa the IDS, it may well pick up on it, but it wouldn't trace back to you, so it dosn't matter if the IDS goes nuts, it
"looks" like a DoS attack, not some one scanning their ports.