There is a couple things for him to do but its practice really that what does it. Here is something that he can do to make him last a lot longer because it has worked a lot for me.
1. Masturbate often and when doing so make it atleast 15 minutes each time. Slowly make it longer and longer until he gets to become very consistent at lasting for a while
2. When the urge of cumming is there, put pressure under the tip of his head on the underside. This will cause bloodflow to slow down and for the urge to cum to go away for a little bit. If this is done frequently it will strethen some of the muscles down there so he is able to last longer.
3.For him to be on his back and you on top. Guys get less sensation when a women is on top so he will be able to last longer since he will get to that feeling a lot slower.