To install download the nodegraphhooks.py file and put it in the python2.7libs directory in your houdini home dir (ie $HOUDINI_PATH). The python2.7libs dir may need to be created if it doesn't already exist. If you already have a nodegraphhooks.py file it's contents will need to be manually merged with this one.
See here for more info about this directory https://www.sidefx.com/docs/houdini/hom/locations.html#disk
The nodes available in the menu for each context and the menu hotkey can be customized in the createEventHandler function at the top of the script.
The default hotkey is Shift+Tab.