This is easily done through the use of the in-game admin panel, which can be opened by pressing
+
simultaneously, so long as you are the host of the game or have been promoted to admin of the game you are in.
For this achievement, you will want start a game in a Star System world. Once you have spawned in, open the admin panel and toggle the "enable creative mode tools" option on. Then, click the drop down menu to select the "Economy" tab, and in the middle of the screen you will see the option to change the reputation of a player. Set the player name to your own and below that select any of the NPC factions listed, then change the amount of reputation given to 1500 (the max) and click "change" to update your new reputation. Repeat the process two more times with different factions in order to pop the achievement. If you are playing with friends, you can also pop the achievement for them as well using the same method, except for by of course selecting their gamertag instead of your own.