2 mins of pushups without stopping? That is intense, you'd be doing like 150 pushups in that time period non stop :S I don't know if that even possible. Are you sure it's not 1 min?
But yeah like Donny has said just increase the time each week by 10 seconds starting from a low number (20) but do plenty of sets so that your doing over 2 mins of pushups, just not in a row. Or you could always do Tabata's 20 seconds of pushups, 10 seconds rest, repeat this 7 more times. Train hard mate.
Bookmarks