You have a couple of options.
You can either have a separate directory for the web controller and follow the instructions that I have posted to the Github site https://github.com/pluggemi/roon-web-controller
Or you can try out the Extension Manager that @Jan_Koudijs has written. Both the Roon Web Controller and the Logitech Harmony Source Control extensions have registered with Jan. You can read the details about his project at Roon Extension Manager v0.7.1