How do you be mickey in Kingdom Hearts 2?

I'm not 100% sure about the conditions but there are a few ways 1) sometimes when you lose at a boss a white screen will appear instead of the game over screen, it'll have two options, "I'm not giving up" and "its all over..." select the not giving up one and king mickey will appear you then have to fight off the boss and charge your drive gauge to revive sora if you run out hp as mickey you'll still be able to continue as sora but with only half your hp 2) use codebreaker, GameShark or some type of cheating/hacking device for PS2