Here's one of those situations where "following the steps" in job hunting and interviewing isn't enough. What matters is knowing how to deal with the one daunting obstacle that crops up... This is the kind of question I get asked a lot:

If you're lacking something that an employer wants, but you're a fit on all other counts, don't wait for the manager to decide whether to take a chance on you. He probably won't. Don't wait for him to figure out what to do with you -- figure it out for him.

Offer to demonstrate what you can do. Few job candidates ever do that in an interview. A good employer who's looking for a confident, talented, dedicated worker will react well. Ask flat-out if he's hesitating to hire you over that one point. Then tell him you'd like to prove that you're a fast learner and that your other skills will more than compensate for anything that might be lacking.