I think you're right to try and wean him off of the bottle because I have read many articles on the negative affects this habit can have. The natural sugar in the milk can promote cavities while the child sleeps and drinking bottles in bed can also raise the chances for him to develop ear infections.
Maybe you could try giving him a bottle filled with water for bedtime and give him his milk as a "reward" when he awakes. My older son (22 months) uses the Nuby sippy cups for milk and I give him a regular sippy cup for the rest of the day. The Nuby cups have a silicone sippy-shaped spout which is kind of like a happy medium between a nipple and a hard plastic spout.
Or you could try making a big deal out of being a "Big Boy" and let him brush his own teeth with a special toothbrush before bed but also make that the cutoff time for drinks.
Different kids respond differently to different approaches but I think you have to expect that no matter what you try, taking away something that he has come to expect will be no easy task. Weaning my older son off of a pacifier was ROUGH because he would awake during the night and cry for his binky. I imagine you might deal with a similar response. Just be supportive and give lots of hugs etc. when he is upset by the absence of his milk bottle. I hope this helps! Best of luck!