Thanks @Robert.Wall, means I have to remember how!
I think all I did was install the emonScripts when it asks if you want to continue you say no (otherwise you get a full emoncms) and then just run the emonhub.sh install script. The only change I made was to switch the branch to the Python3 branch as that was partly what I wanted to test.
You then need to configure emonhub, but it works pretty seamlessly.
This link will help