How does one treat this?
I've never had experience treating this kind of problem, but centers do exists for such a thing, just as their are counseling centers and hospitals. Many who suffer from same-sex attraction are helped out of that lifestyle through the help of such places. I imagine Exodus International has information on this.
It starts with the individual surrendering to the power of the living God, or the Holy Spirit, in faith that a force greater than the self can achieve what the individual cannot. The person may work with a pastor, therapist or counselor who is trained to support people struggling with these issues, or he or she may rely on some combination of prayer, scripture study, workshops, journaling or various other approaches. Release and healing may take years and thus it requires patience, and friends who are supportive in faith that God is still working miracles to this day.
A very good question. Overcoming same-sex desires is no easy road but it is indeed possible. Below are some links where homosexuals can get help leaving the lifestyle.
BTW, we have ex-gays on FreeRepublic.