How do I meet boyfriends 4 year old daughter?

My boyfriend and I have been together a little while now and he wants me to meet his 4 almost 5 year old daughter, but what's the best way to do this?. I don't want her to dislike me and I know it will take time because I'm someone strange, another woman in her dad's life and the fact that I'm not her mother. She can be a hand-full anyway and her mother is reluctant for her to meet me in case she gets on better with me as they don't get on brilliantly anyway, please help!!! I want what's best for my boyfriend and his little girl but were moving in together and he wants her to stay with us and go out together etc etc. How do I make her feel comfortable around me and what would you suggest for our first meet? Please help, thank you!