Although personally I’ll be absolutely ecstatic if and when this day comes, being overqualified for the positions you are applying for can be a major setback. This does not mean, however, that you cannot successfully pursue these positions. How you handle the situation can quite possibly be the making or breaking factor when this “issue” arises.
First, be upfront about the situation. If the interviewer brings up the concern, then talk about it openly. Let them know that you value the company and would not leave the second a better opportunity elsewhere arose. If you can provide the employer with a compelling reason as to why you want this specific job, even though you are overqualified for it, you’ll have a much better chance at being successful.
When the issues arises, you can also ask the interviewer to more specifically discuss the daily tasks involved with the position. It’ll be your job from there, then, to explain what it is about these tasks that motivates you to apply for this position. Perhaps these tasks are not your specialty and you’re eager to have the opportunity to master them. Or maybe you enjoy these tasks and would therefore find this position personally fulfilling. Whatever the reason may be, this all goes back to convincing the employer why it is that you want this position so that you will not be cast off as an overqualified job-hopper.
If you’re really having a difficult time convincing the interviewer that you’re not going to flee at any moment, offer to sign a contract binding you to the position for as long as you are comfortable. While hopefully you won’t have to make this offer, if you desperately want this position and cannot find another way around the over-qualification issue, then this option can always serve as your last resort.
And lastly, remember not to get too frustrated. Although it may not be what you want to hear, it’s a compliment to be told that you’re “too good” for a job.