Hi Haemophile,
I've moved your thread to the Tournaments forum, where hopefully someone will be able to give you a good reply.
Sadly, I can't really give you any good advice on this myself since I'm not a 6-max tournament player...
From what I could gather, though, MTTs are played in a similar way to cash games in the early phases, so maybe these two articles could be a decent introduction:
Shorthanded Theory
Shorthanded Pre-flop Basics
Hopefully, one of our tournament regs can give you further advice.