Sorry, now I read my post with fresh eyes I can see I was not being very clear.
The original post appeared to be stating that it was not possible to run STOS from a HD unless it was in placed the Auto folder, I was trying to indicate that it is possible as I have run both STOS and STOS 3D from a HD on both an ST and Falcon, I think I also did it on a HD partition under STEEM but gave up with STEEM years ago as it was not responding to some keyboard characters at the time.
For STOS as I recall I just created a STOS folder on my HD and copied all my STOS disks in to that and edited BASIC.BAS to either point something to the correct folder or REM it out. From the ST desktop I had to navigate to the folder and double click either BASIC.PRG or BASIC .TOS (can't remember which) while on the Falcon I had it set up as a Desktop Icon. I can't remember if I put STOS 3D in the same folder as STOS or a folder of its own.