Fallout: New Vegas
You are correct. If one uses a console cheat during the game, then achievements cannot be had. From what I have experienced, the only way to get the achievements is using the consoles cheats right before you leave the doctor's place in Goodsprings for the first time after starting a new game. Just make your character totally leveled, uber powerful with uber powerful weapons (made with the Geck) and already loaded with most items you would need. Then save the game, quit, the reload and venture on.