The taste is quite variable anyway, it depends on the guy and on what he's been eating and all sorts of things besides (I have heard that diabetics have quite sweet semen, for example). I hear that eating fruit makes it taste better (I think there are meant to be certain fruits that are particularly good), and lots of meat or onions or garlic will make it worse. I think you'll get used to it though, I remember finding it horrible at first and now it doesn't bother me, but I don't know whether that's down to me getting used to it, or the fact that I now have a different boyfriend...
Also, if you intend to swallow, then if you arrange things so his willy is quite far into your mouth when he ejaculates, you'll swallow it automatically without really tasting it except a bit in the back of your mouth. Useful knowledge, that.