This girl likes it. And I have quite a few female friends who are also fans.
Unfortunately, this is going to be the area where you well-endowed gentlemen are going to experience the most discrimination. If anal sex isn't done right (and "right" is different for everyone), it hurts, even with the small-small guys.
Best way to find out is simply to ask. If she points to your dick and says, "Not with that thing!!!" then see if she'd be okay with a little finger or tongue play instead. Maybe get a really small dildo or buttplug to get her used to the feeling. Make sure she's... um... cleaned out (has gone that day, hasn't eaten Taco Bell, etc), and if she's really shy, tell her to take a shower or bath and you'll devour her after that. Use lube. You might even want to try mixing in some of that numbing stuff that's supposed to make men last longer. It might lessen the pain.
Go slow. Got it? S....L....O....W.... Listen to her. If she winces, stop and pull back a bit. Keep talking to her, kissing her, touching her, telling her how hot she is. In short--if it's her first time and she's really nervous, keep her mind off the fact you're getting all up in her ass.
Anal does feel pretty good with the right partner. After some good licking, fingering, toying, she might just let you graduate to the real thing. Again, that's a take-it-slow thing. You might only get a bit of the tip in the first time before she asks you to stop. Let her go at her own pace. She'll be more appreciative of the respect and more apt to let you continue on.
Also: I'm personally more apt to try something that I know my partner would try as well. Maybe if you were willing to also take a finger, tongue, dildo, strap-on up the ass, she'd be more keen to let you do her as well? Approach it as a learning experience? One of my biggest fantasies is having a Bend-Over-Boyfriend and if I ever find him, he's welcome to my ass anytime he wants.