Those bolts on your last pic need to be taken off in order to get the shelf panel out, I can't recall correctly, I remember there are 3-4 that hold the shelf in place, but seems like you are in the right direction. I think it is from BSW's utube speaker installation instruction that had mentioned about it as well ( they didn't show it as the demo car do not have the shade shelf panel).

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96 528i AT w/steptronic. => 97 540i w/ steptronic.