How to Install iTunes 11 (and 10) on Mojave

[ljmac]

When I first saw this software I was excited by the possibility of installing iTunes 11 on my Mojave Macs, but it seems this can only be done on Catalina. However, if it is possible on Catalina, then surely it must be possible on Mojave too, right? If so, can you tell me how to do this myself, or add this functionality to Retroactive? I am happy if it still has to use the 'guts' of 12.9 - I just want the iTunes 11 UI and library format (for compatibility with my older Macs).