Well, all I can say is GOOD LUCK!
With a 6am flight you're getting there around 4? Waking up at...earlier than 4.
We did that with our first trip to Disney (well, San Diego with one day at DL), thinking what your'e thinking, and it sooooo didnt' work out. He was so intrigued by the shuttlevan to the airport, then the airport, then the plane, that he was up up up the whole flight. We, on the other hand, were disturbingly tired.
The one good thing is that he was still (still is) nursing, which is always one of his favorite activities.

So a few times I could just hold him for milk, which gave us a brief respite from the squirmyness of a...hmm, 16 month old.
If you think there is ANY chance you might have an extra seat next to you that they would let you use, bring that carseat and hope hope hope.
When we flew last year, when he was around 27 months old, I loved loved loved the carseat. Other than an absolute infant, I won't do the lapbaby thing again. Carseat was MUCH easier.
Stickers were a big thing last trip, stickers galore. Papers, crayons. We've since acquired a portable DVD player and I KNOW that's going in our travel bag in September.

I've noticed that some airports have rental players, maybe yours does, too?
But I hope your wee one sleeps. That would be the easiest.