I got lazy and didn't oil it, my shocks don't have the slot, but thanks to my dremel and your post they will have one by days end
It didn't even cross my mind to slot the top of that damn thing. Also I found that wedging a wide bladed screw driver at the top to get the 17mm wrench in there works well also, and if you lack a vise you can just set the bottom of the shock in place on the bike itself leaving the top unattached for the dismantle.