LOL! Oh, I get it now! I found putting my finger in my kid's mouths when they were under 3 months was just fine. I have never heard of a baby becoming 'addicted' to their parent's fingers, so I wouldnt worry too much. Most women I know just pop the baby on the boob to quiet them down, so I guess a finger is better 'cause then both parents can do it!
As for advice on how to get them to take a passy or suck their own finger/thumb, I would say just be repetitive and dont plan on it happening too quickly.