I wrote a new handy script (install_1013_DP4_17A315i.sh) to install macOS High Sierra Beta DP-4 .
The installer.pkg created by the script will simulate the App Store download and installation method, and all you have to do is:
1.) Run script
I have yet to try this script myself. I ran the script myself and got a nasty surprise – the target HFS volume was converted to APFS.
Edit: The (blue) checkbox in the installer, the one that enabled us to skip the conversion of our HFS volumes to APFS, is now gone. This is why I have updated the scripts (environment variable __APFS_OPTOUT added to skip the conversion) but this may not be enough. Please confirm.
Please note that the App Store.app downloads files to: /Library/Updates but the script uses: /tmp/091-* and all the downloaded files will be gone after a reboot, and thus you may want to make a backup of the files!
I also wrote a handy script (update_DP4_17A315i.sh) to update macOS Beta DP3 to DP4.