I'm of the mindset that they don't deserve to go to the playoffs but I'll watch the game and root like hell for the Bills because I never like to see the Steelers football season come to an end. You never know if it will be your last.
All that being said, when it comes down to miraculous scenarios that had to come true in order for the Steelers to make it into the playoffs I go back to Chuck Noll's last trip to the post season in 1989. They needed:
1) Win final game at Buccaneers
2) Saints Win
3) Giants Win
4) Vikings Win
All that somehow worked out and they went on to snag the last wildcard and win at Houston (the Oilers) on New Years Eve. I remember that game and celebration afterwards like it was yesterday. The following week they came damn close to upsetting the Broncos and lost by one stinking point. I remember driving home that night seriously pissed off. Made last weekends loss equivalent to getting upset at a partly cloudy day.
Here is a great article on that scenario and the 89 Season:
http://www.cbssports.com/mcc/blogs/entry/12411205/12853966