Generally, I'd say that once you find your problem breaking into the real world, that's when it can become a problem. Is it possible for you to focus on guys you find attractive without imagining them getting raped? My first suggestion if you find yourself running astray with your thoughts, I'd try to immediately think of something else. There's a few things that have helped me in my own struggles that I think might help.
First of all, try to imagine yourself being in their position. I feel I should label this right now as *TRIGGERING* just in case.
I'll use a sort of analogy here that maybe it's not a person, but rather a big stack of rocks pinning you down. Like perhaps you're in a burning building and a large beam has fallen across your torso.
Imagine that you yourself are pinned down, and the weight on top of you is such a huge pressure that you feel your insides are about to burst open. Then imagine for instance, let's say there's a huge fire poker that's extremely hot, and this device is being shoved deep inside you repeatedly, charring and burning your organs. The pressure of the heat mixed with your breathing and gasps of help only make the weight on you feel worse. Somehow you're still alive, but you wish you weren't because each breath you take is numbered, and you realize that even if you do make it out alive, you'll never be able to forget this experience. It'll always stay with you, that feeling of helplessness. And still, the part you'll never forget is that burning hot iron, searing your skin, smashing your insides, and in all probability, literally breaking you apart from within. The heat burns, it stings in a way you never thought possible.
That, I imagine, is how a victim of sexual abuse must feel on some level. Sorry if that's graphic, but I'm trying to paint the proper picture of this without being too triggering.
I would never take pleasure in that, if someone was watching me and enjoying the sight of me stuck under a beam in a burning building, I don't think I'd ever forgive that person.
Just a thought.
Now as far as reconditioning your mind, there actually happens to be a great thread right here in the Paraphilias forum =)
It's near the top of the list and was posted by a moderator. It's Paraphilias: Treatment and Medication and what I started doing is if you hold that image that turns you on if you're masturbating to it and nearing orgasm, you switch the fantasy in your head to a more appropriate thing. As you keep doing this over time, you keep switching at earlier and earlier stages of your masturbation to that fantasy and eventually, it's supposed to help you recondition yourself to a certain degree.
Remember that your attractions may not leave forever, but this is certainly a better way that I've discovered to help myself. Since I'm pretty non-exclusive in my hebephilic attractions, I'm finding it easier to cope with that way.
Other methods are if you find yourself falling into that, get away if you can. Distract yourself.
Some pedophiles on this forum take whatever approach is best for them. For me, I don't feel comfortable seeing myself as evil incarnate or a horrible person, because I guess it works for some people to get angry at themselves or others and wage a constant war against themselves, but my own approach is more passive-resistant.
For example, it's easier if I'm focusing on what I love to do. I'm a self-published author and write stories, not necessarily involving my attractions, but I write very symbolic things and enjoy exploring the depth of human emotion, psychology, philosophy, religion, etc. because at the end of the day, my writing is what matters most to me.
I also produce electronic/dance and dubstep music, so that helps me in some ways too (I find the extreme bass and heart-stopping beats to be somewhat comforting lol).
But we all have our own ways of dealing with this, and it's not something you may deserve or even asked for, but it's there nonetheless. To accept it or perpetuate it only makes the attraction worse. You just need to find ways of distracting or calming yourself, and though it may be sexually frustrating for quite some time, it will pay off in the end because it doesn't mean that your sexuality dies, it just means you have to channel it properly and in healthier ways.
It is possible to find other things that will satisfy you, it just might take a while.
For example, when I was a teenager, I used to be attracted to both boys and girls, and I won't deny the part about girls even if I do now label myself as gay and have no experience with girls, I was still attracted to them.
I think what our mutual main problem is, is that we found one thing that really really got us turned on and going to the point that we started to deny all other possibilities, and that's one of the biggest problems in why I think we also feel so isolated is because we felt something that we inherently know is wrong or taboo or disgusting, and we were so ashamed we felt that way that we retreated into it because though it's sexually comforting, it's also shameful.
So I think it's also important not to close yourself off from more healthy possibilities.
Don't perpetuate it by fantasizing, because though now you may not be hurting anyone, you're only hurting yourself in the end because it will make you desperate, angry, upset, and frustrated.
If there's other things you love doing, I suggest you focus more on that and try not to think so much about your fantasies or how they're so wrong, because if you give too much attention to the thoughts of yourself and how horrible you think it is, everything else that's good in your life will suffer and you'll feel like some empty shell all because of this thing.
There's a lot more to people than sexuality, it's just that when that deviant fantasy of sexuality starts becoming more dominant, you let it take over, and I'd really suggest you not do that.
Don't worry too much, don't freak out, but don't perpetuate it either. Find things that are calming until you feel more comfortable to try out a new fantasy that's more appropriate, and don't chastise yourself if you fail at first, cuz that's to be expected.
Just take your time with yourself, get to know yourself and focus on other things for a bit.
I think that's the best advice I can give right now and I sincerely hope it helps =)