Well, if you want to do it quickly, I think it'd be kind of easy in a place like France, since it starts out with a good deal of power. That's the real issue: being able to defend yourself from just about everyone looking to expand. Which is everyone.
Just do the same thing, but at the same time imprison every land owner you can get your hands on, legitimately at first but then getting more proactive once your ruler starts getting ready to leave the mortal coil. Then banish the whole lot of them, and divvy up their land to your chosen people while keeping the best bits for your heirs. Doing so will make you a lot of enemies, so there's a good chance you'll end up dead one way or another. It might be a bit easier than the way I did, since you don't have to wait for the 'conquered by different religion' nonsense (sore losers!) to clear up on most of your land.