Hint - Unit Cap Hack:
Changes game critical files. Back up the originals before alteration.

Locate the ini.big file in the game directory and open it with a text editor such as Notepad. Search for the following string:

GoodCommandPointLimit = 300
EvilCommandPointLimit = 600

And ajust the amount to what you want. It is a good idea to look below that string for more values to adjust, such as:

GoodCommandPointsBonus = 20;
bonuses for every territory captures in living world
EvilCommandPointsBonus = 50

and add about 30 or so to each value, depending on how high you set your command limit, as it will not be possible to reach 999 command in campaign when you only get 20 or 50 bonuses per terrain.