What I found was the easiest way to earn this achievement is by using the intermediate play controls on rookie difficulty and unlimited rewinds.
Once you begin to choose a play, change the formation to 'Switch WR' (using LB/RB) and make your WR your running back instead. Because of that player's general speed vs. the original RB, you can get more distance, if not 1 play TD's out of him.
Good luck. Remember, the longer you set the quarters too, the easier you can accumulate 300 rushing yards... doing this method, I managed over 500 rushing yards total in 3 min quarters.