In WinSCP from the launch window select your connection then Edit>Advanced>SCP Shell>and change it to sudo -s then save. This will give you root access to the Pi filesystem so be careful, when done change it back or make a second connection for normal use. Also in SCP settings it would be wise to change the default editor to Notepad ++, obviously you will have to install it first, this will preserve unix line endings when editing files which will save headaches.