As long as you don't feel you would be in danger by doing so, I say tell him. I recommend finding a non threatening place to tell him as well. If your in college, your dorm room is not a good place to have this conversation. I've had friends in the past who were slightly homophobic tell me that me coming out to them and then hearing my story actually made them think the issue over and gave them a different perspective and now they are great GLBTQ allies. Whenever possible I think it is our responsibility to educate people on how we're just like everyone else and just as deserving of respect as anyone else. If it works out, be prepared for 1. Your friend either to be super sensitive in trying not to offend you, 2. Your friend continuing to make homophobic remarks without realizing it. 3. Your friend completely ignoring your sexuality, or 4. Your friend to think your coming out to him because you have feelings for him. For 1. you'll want to let your friend know you don't want them walking on eggshells around you and you'll be honest if something does offend you and be open to discussing it. For 2. you need to be patient and explain what the homophobic remark is litterally saying i.e. 'that's so gay for that's so stupid/feminine/uncool is not just a saying but a method to belittle gays and make being gay synonymous with something undesirable', how it makes you feel, and how it could make other who overhear feel 'good place to quote that GLBTQ teens are at extremely high risk of suicide and being exposed to intolerance increases that risk. For 3. you really have to get it through your friends head that taking an interest in your dating/love life does not mean that your going to start blabbing about your sex life and talking about giving blowjobs and anal sex. 4. Tell your friend to get over himself, just like he doesn't find every girl attractive, you don't find every guy attractive, and just like he, i hope, doesn't force himself on women, you do not force yourself on men.
Best of Luck, Let us know how it goes !