To spell it out, the feature you link to does not provide any new options in the editor.
It modifies the /nodes admin http endpoint to support a url parameter that can be used to provide a installation source url for a node. Within the editor, the catalog format has also been updated so entries in the catalog can include such a url.
However - this doesn't mean you can now just pass a URL to the /nodes api by itself - you still need to provide the module name that will be installed from that URL.
Coincidentally, I opened a design PR yesterday to consider adding the ability to upload a node's tgz file directly via the /nodes api - as well as the UI changes to the palette manager so it can be done fro the editor - https://github.com/node-red/designs/pull/35
Whilst writing that, it became obvious that we lacked the ability to do what you're asking here - provide a way for the user to provide a url directly in the UI. That may get rolled into the above design as well.
As an aside, the /nodes docs haven't been updated to reflect the support for url - I need to make sure PRs that modify the admin API also drive issues to be raised against the docs so things like this don't get overlooked.
The reason for my question is that - from time to time - I ask users to install and test a new fix/feature directly from my github repo. And some of them continiously fail to do that, so then I have to publish the test version on npm (which I don't like ...).
Not urgent, but nice to know that it will be available in the future!