Well, we all know that you need an amount of points to reach a certain rank.

You can do that until you reach the level of Brigadier General (57700 points).
After this you don't need any more points to promote.

I've searched quite alot since I promoted to Brigadier General, and I still haven't found out how to promote to:

1. Major General
2. Lieutenant General
3. Supreme Commander

Anyone knows to promote to these ranks specifically?

I doubt anyone except the good people at EA know how this works.