I have a couple of deep scratches on the rear door above the window. would it be possible for me to use the above method but without the machine polish and just do it by hand?
firstly i would say only attempt this if you are confident about wet sanding and understand fully the methods involved as you could end up doing more damage,
no you really need a rotory or a DA to buff out the sanding marks,i had to do several passes with the rotory to get the finish i wanted, you'll be there forever trying to do it by hand.
my advise would be get someone to do it for you if you havent got all the necessary equipment.