Go into the main folder, and open up the "Wizards" folder. In here go to the file _start.wzd, and open in any text editor (Textpad, EditPlus, whatever.)In here you can change any attributes of Cornelius at the start of the game. This means, if you want it to take effect, you will have to play the game from the beggining.
Note: If some values go past their maximum, your game will crash. This also goes for if you unlock items and spells by erasing the ; at the end of the line.Using this, you can also change the attributes of all the enemy wizards in each level as well by going to the appropriate level number, and doing the same.