A bit off subject BUT I like hot (uncomfortably so) to do fast draw holsters. I have often wondered of alcohol would have the same affect?? Some of what I have read by Chuck Burrows would indicate otherwise though. Heat hardins and alcohol just dries the leather?
To actually harden the leather permanently it's the heat that does it and that does not occur until it's over 140 ͦ F and does not make the change on the molecular level until 160 ͦ F. Under those temps even hot water only hardens via displacing the oils and fats in the leather as does alcohol and other solvents.
As for stretching yes alcohol will work fine but will definitely require re-conditioning, but the down side is it may over dry the leather to the point that even re-conditioning may not work without some damage - bottom for me is to use solvents including alcohol as little as possible, water while slower is generally overall the better option. albeit even that can cause damage that may be unrepairable. IMO doing leather repair is one of the best teachers I found over the last 50 years that there is for finding out what does and does not work.