The description for this Achievement is a little misleading. It sounds as though you need to score a TD on an 80-yard play, but in fact you just need to score at the end of an 80-yard drive. It's also a little nebulous as to what is meant by "near the end" of the second quarter, so to play it safe, just try for this in the third or fourth.
When you receive a kick-off or a punt, dive to the ground somewhere on your own side of your 20-yard line to ensure that your drive will span the required 80 yards. On easy difficulty levels, this should be no problem to achieve, just focus on plays you're familiar with and have had success with. Rushing plays with Barry Sanders work well, especially on tosses to the outside. Or form a team with a gold QB and gold WR and launch some deep passes.
The Achievement will unlock after snapping the ball on the point-after attempt after the touchdown has been scored.