It LZX the setup of a version (approximately):
1, transfer it onto Amiga, you are on Amiga download it.
2, TIP: (If there are 2 partitions, but only one can be bootable (ex:Dh0). Do it the 2. (ex dh1) partition being files save it into one dir (ex: create new folder name Myfiles), move your all files into Dh1:Myfiles.
3, unpack AmigaSYS3AGA.lzx into Dh1.
4, start Hdtoolbox, settings: unbootable Dh0, bootable Dh1
Reset...
Amiga booting from Dh1

I wrote this down because of that. Because your present system remains in this manner. Many people like it the HDF otherwise.

2. point only idea. I got accustomed to it in this manner.