R.B.
I would sit down with him today and explain this is why you would like the help.. after doing it, now he should understand.
Tell him to give it another shot. Lay out all the kids clothing and shoes so its ready to just put on in the morning and have breakfast set up so all they have to do it get it ready and eat it. Then give him a schedule... x wakes up at this time, all should be dressed and breakfast ready by this time. Leave by this time. It should go easier if everything is set up and ready to go and he can see what time everything needs to be done by instead of doing it by the seat of his pants.
If that still doesn't work then tell him you will do the mornings but he has to do the afternoon pick ups. Again write all the times for where they need to go and pick up times. If he has it written out he should be able to do it, tell him its not going to go smoothly the first time but you would appreciate it if he tries to help. Even if it doesn't go well.. still thank him for his effort, wether it was a great effort or not.