For anyone (like myself) who (i) does not know what the VLSC is, or (ii) when he/she finds out what it is, realises that it is not available for mere punters (maybe it is, but the front page is off-putting):
It would appear that the required folders are on the W10 install DVD (or ISO), inside the 'install.wim' file: G:\sources\install.wim\1\Program Files\WindowsApps\. One can use 7zip to view the contents of the .wim file, and extract what one needs to the WindowsApps folder on C:. Then add the packages as detailed above. I had to take ownership of the WindowsApps folder to be able to write to it. Hope that helps someone the way this page helped me!