NHL 10

I came across this youtube video made by "AchievementsRock" of a fairly simple way to obtain the achievement.

Broken down the method consists of you picking a good team, against a badly rated team through the "play now" game mode.

Settings to hardcore and skill to rookie, before the game begins move all the sliders to your benefit. Also ensuring your injury occurrence slider is maxed.

Have the player you intend to try to score with run into the boards, injury themselves in a fight, get checked hard...etc. To cause an injury.

Once the player is injured, pop in a goal with them and the achievement should unlock.

First you need to have an injured player. You can turn up Injuries in the settings pre-game to increase the odds of this happening. I had 2 get hurt while fighting. You will have the option for them to keep playing. You may have to bench them, then tell them to keep playing. The easier way is to have them play the following game (if a playable injury), then score in that game, since you will have more time. You can put them on every line to give yourself more chances, but I didn't bother. I just got it this way, so I can confirm it doesn't have to be in the same game the injury happens.