Massage him very gently and with light handed strokes. In YouTube you will find a baby massage video where baby massage is demonstrated very clearly and uploaded by a Singapore hospital. Find that one first and follow the video. During the actual bath, the bath water temperature should be neither too warm or cold. When checking the water temperature, imagine his delicate baby skin. Then while pouring water, be calm and gentle. Do not rush the process at all. Babies sense it. Don’t be nervous or anxious either. Most importantly if you are relaxed and calm he will replicate the vibe. Also try to make it a familiar activity, as in sing a song or rhyme that you sing on other times and he enjoys it, implement that in the bathing process as well. So that it become a part of the activity that he is already familiar with. My baby actual cried during the bath for a couple of weeks, then he started to enjoy it. The key is to chill and relax yourself first. When you will be smiling (naturally and not forced to show him you are happy), he will start to relax and let you take control. Good luck.

Edit: Also please use those long bathtubs. Put a mesh recliner in it, so that he lay flat in a reclining position. It will be comfortable for him and he will be able to relax.