That's the saddest thing, there's no way to really meet them in real life
The social outcast girl is the hardest kind of girl to find in real life. Your only choice is to possibly try online dating maybe?
If it's just a comic nerd or gamer girl with some to little social contact, then game tourneys and cons are always great places to find people like that.
The only way I know some of the girls I know is through friends and friends of friends.
If you have friends in school or possibly even friends from a job or something, see if they know anyone like that. You never know who people know until you ask them.