Being able to pressure from a 4 man rush is the single biggest key. Indy was able to do that for the first half and much of the third, but two things changed: Mathis and Freeney ran out of gas and the Pats switched to hurry-up, all-shotgun offense.
The Steelers have a great defense and are more physical (and bigger) than Indy, so I don't expect them to run down as Indy did. But they will likely get less pressure from their base defense, and that is a problem...because no secondary has been able to cover the Pats if Brady gets time. You can blitz, but teams against the Pats this year have tended to get burned on 1 huge play for every couple of pressures when they blitz and that's actually a pretty bad trade-off (unless you knock Brady out on the pressures!)
So, I think being able to get some pressure from the front four, judicious use of blitzes, and the aforementioned quality safety play which prevents the huge plays...you can give 20 yards but don't let them get multiple 40+ yard plays.
Tough prescription, and no team really is well-built to deliver. To me, while I think Pitt is a better team it is the Giants who the better personnel for this particular gameplan.