I think it may also help if you could develop a theory about the meat yourself. Currently, these feelings that you have are most likely mental-only, that is, it's probably not that you have an allergy etc. caused by the substance in meat. So, a good way to solve this problem is to give your mind a new and healthy way to think about meat. As a result, the next time you see meat, you will have (most probably) this new theory towards meat in your mind, and you will feel saner and calmer.
As to what this new perspective towards meat can be, I think that you should try to figure it out yourself, as what may work for one may not work for another (since different people have different mentalities and experiences, hence any stimulus will elicit a different response in both). For me, I rather think about the person eating it - I feel sorry for them. Most probably they are ignorant about the truths behind what they are eating, no one has shown them the facts or the torture etc. Since this brings out a feeling of compassion in my mind, I think it overshadows the feeling of disgust - plus this thought is powerful for me, so it just does not allow me to think about anything else (and you can invariably think of only one thing at a time).