Yes, it is possible.
But only with planets in a saved game. So you would need to start a game, save it, then edit the saved file to add the bonus tiles.
I can detail how to do it in DL, but not in DA or Twilight.
You need a hex editor (I use Hexplorer), the planet name and the correct values to insert. The values may have changed from DL, so I can't help you there.
You can't change the random generation of planets, however. That is hard coded.