[LINUX MINT 17.2] Mouse middleclick paste keybinding

Install xdotool

$ [sudo] apt-get update -qq && \
> [sudo] apt-get install -yqq xdotool

Then add a custom shortcut

System Settings > Keyboard > Shortcuts > Custom Shortcut > Add custom shortcut

Add whatever shortcut combination you want targeging the following command:

xdotool click 2