To do this, simply find a door that doesn't take you to a loading screen when opening it (Fort Urasek has a perfect place for this). Simply go in to sneak, and walk against the door and your level will increase so long as you are not heard. This means that if you are below Journeyman if you sneak too fast you will be heard. All you'll have to do is sneak off until you hear the fight music turn off, then sneak back over and continue. I used a paperclip to hold my joystick forward so I didn't have to hold it myself, and checked back once an hour or half hour to hit X when I got to each next Sneak level, and by morning I was a Master. This opens up plundering fools like no other, as well as most enemies you can keep hitting for 6X damage. If they have high security, or another enemy sees you whacking away at 'em you stand a chance of getting caught, but if you keep sneaking, or better yet put on an invisible spell potion, you can sneak away and they'll lose track of you. I've found that high damage bow and arrow combinations are the best way to never get caught.