It's a simple set of commands to achieve this.
First make sure you have nemo installed
sudo apt-get install nemo
Then change the defaults to nemo:
xdg-mime default nemo.desktop inode/directory application/x-gnome-saved-search
gsettings set org.gnome.desktop.background show-desktop-icons false
gsettings set org.nemo.desktop show-desktop-icons true
Test it with this, it should answer "nemo.desktop"
xdg-mime query default inode/directory