Using Parallels 14, I just pointed it at the “Install macOS 10.15 Beta” app, and let it go from there.
I tried on my 2013 MacBook Air, but it had issues and didn’t work in the end - it had the same issues I’m about to describe but it ended up in an error message. My Hackintosh is pretty beefy (i7-4790k, SSD, 32GB RAM, RX580) and even it struggled a bit keeping up. My CPU didn’t get over loaded, but there is definitely lag...
So! Installing it - it took a while to boot to the installer, but once it did, followed the steps. It hung up at “2 minutes left” - I let it sit for a few minutes and made sure that Parallels reported no disk activity before resetting the VM. It booted again, and started doing the main install with the black screen and white progress bar. This time it got hung up at “less than a minute remaining”; after giving it about thirty minutes, I force reset the VM one more time, and it booted to the setup screen properly.
Very much an unorthodox install, but hey it worked! I get no graphical acceleration but that’s probably to be expected for running a newer OS within an older one.