On PC: You can get this legit or you can use console commands.
Press the tilde (~) to open the console.
If you do this near the start of the game, you should be on neutral karma. If not, use the command "rewardKarma [number]" (without quotes)
Then enter "player.setlevel 8" (again without quotes). Leave the console and wait for a bit and the achievements will unlock.
On Xbox: Get to good Karma, then just before you finish a quest to get to level 8, either go on a small killing spree to get ot neutral or a big killing spree to get to bad. Keep reloading the save until you have all three achievements for that level. This way you don't have to play thourgh it more than once.