I recently reinstalled Zorin OS and understand that downloaded cursors should be extracted and put into /usr/share/icons. However, I do not have "permission."
@Storm is correct; cursors will appear by your chosen theme whether placed in Root or in Home.
But you may want to place Icon themes in /usr/share/icons
So for future reference:
Open terminal then elevate to root;
sudo -i
Then launch Nautilus from the root terminal:
nautlius
Navigate to the directories you need to modify.
Other locations (left pane) > Computer (right pane)